llama.cpp/docs/autoparser.md

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Auto-Parser Architecture

The auto-parser automatically analyzes chat templates to determine how to parse model outputs, including content, reasoning, and tool calls.

Overview

The unified auto-parser uses a pure differential, compositional approach (inspired by the git diff algorithm) to analyze chat templates:

Core Philosophy:

  • Minimize Hardcoded Patterns: All markers extracted through template comparison (the only heuristic is JSON detection to distinguish JSON_NATIVE from tag-based formats)
  • Compositional Architecture: Separate analyzer structs for reasoning, content, and tools — each responsible for its own analysis and parser construction

Analysis + Parser Building in Two Steps:

  1. autoparser::autoparser tmpl_analysis(tmpl) — runs all differential comparisons and populates the analysis structs
  2. autoparser::peg_generator::generate_parser(tmpl, params, tmpl_analysis) — uses the analysis to build a PEG parser and optional GBNF grammar

Data Structures

All structs are defined in common/chat-auto-parser.h.

Top-Level: autoparser (main analyzer and generator)

common/chat-auto-parser.h:367-388 — top-level analysis result aggregating jinja_caps, reasoning, content, and tools sub-analyses, plus preserved_tokens (union of all non-empty markers).

analyze_reasoning

common/chat-auto-parser.h:254-274 — reasoning analysis result: mode enum, start marker (e.g. <think>), and end marker (e.g. </think>).

analyze_content

common/chat-auto-parser.h:280-295 — content analysis result: mode enum, start/end markers, and requires_nonnull_content flag.

analyze_tools and its sub-structs

Enums

reasoning_mode: How the template handles reasoning/thinking blocks.

Value Description
NONE No reasoning markers detected
TAG_BASED Tag-based: <think>...</think> (start can be empty for delimiter-style formats)
TOOLS_ONLY Reasoning only appears in tool call responses, not plain content

Reasoning Prefill: Extracted in generate_parser() using compare_variants(add_generation_prompt=false, add_generation_prompt=true) on a minimal single-user-message input to get exactly what the template appends as its generation prompt. The start marker is then located within this suffix using rfind. Three outcomes:

  1. Start+end in generation prompt (e.g. <think></think>\n): prefill = start + end. The parser sees reasoning as opened and immediately closed.
  2. Only start in generation prompt (e.g. <think>\n): prefill = from_start (substring from the marker's position to the end, preserving whitespace). The parser sees reasoning as already open.
  3. Start marker in the generation prompt but not at its end (e.g. Apriel's <|begin_assistant|> followed by boilerplate): the marker is a template artifact. The start literal is cleared from the parser so reasoning uses delimiter-style (end-only). For templates that ignore add_generation_prompt (empty diff), the rendered data.prompt is used as fallback — but only for non-TOOLS_ONLY modes, since in TOOLS_ONLY the start tag is model-generated and may appear in prior conversation turns.

The prefill is prepended to model output before PEG parsing, fed to the grammar sampler via llama_sampler_accept, and used to determine the reasoning budget sampler's initial state (COUNTING if prefill starts with the reasoning start tokens, IDLE otherwise).

content_mode: How the template wraps assistant content.

Value Description
PLAIN No content markers
ALWAYS_WRAPPED Content always wrapped: <response>...</response>
WRAPPED_WITH_REASONING Content wrapped only when reasoning is present

tool_format: Classification of tool call structure.

Value Description
NONE No tool support detected
JSON_NATIVE Pure JSON: {"name": "X", "arguments": {...}}
TAG_WITH_JSON Tag-based with JSON args: <function=X>{...}</function>
TAG_WITH_TAGGED Tag-based with tagged args: <param=key>value</param>

call_id_position: Where call IDs appear in tag-based formats.

Value Description
NONE No call ID support detected
PRE_FUNC_NAME Before function name
BETWEEN_FUNC_AND_ARGS Between function name and arguments
POST_ARGS After arguments

Tool Calling Formats

JSON_NATIVE

Structure: The entire tool call (function name, arguments, values) is in JSON format. Optional enclosing tags around the section.

Detection: Function name appears inside a JSON structure (quotes preceded by { or :).

Examples:

Standard OpenAI-style:

<tool_call>
{"name": "get_weather", "arguments": {"location": "Paris", "unit": "celsius"}}
</tool_call>

Mistral Nemo with array wrapper:

[TOOL_CALLS]
[{"name": "calculate", "arguments": {"expr": "2+2"}}]

Function name as JSON key (Apertus style):

{"get_weather": {"location": "Paris"}}

TAG_WITH_JSON

Structure: Function name is outside JSON, in tag attributes or XML-style tags. Arguments are a JSON object.

Detection: Function name not in JSON, but argument names appear in JSON context.

Examples:

Functionary v3.1:

<function=get_weather>{"location": "Paris", "unit": "celsius"}</function>

MiniMax:

<minimax:tool_call>
<tool_name>calculate</tool_name>
<arguments>{"expr": "2+2"}</arguments>
</minimax:tool_call>

TAG_WITH_TAGGED

Structure: Both function name and argument names are in XML-style tags. String values are unquoted; non-string values are JSON-formatted.

Detection: Neither function name nor argument names appear in a JSON context.

Examples:

Qwen/Hermes XML format:

<function=get_weather>
<param=location>Paris</param>
<param=unit>celsius</param>
</function>

Mixed types:

<function=calculate>
<param=expr>2+2</param>
<param=precision>2</param>
<param=options>{"round": true}</param>
</function>

String values (Paris, celsius, 2+2) are unquoted; options (object type) is JSON-formatted.


Analysis Flow

autoparser::autoparser(tmpl)
    |
    |-- Phase 1: analyze_reasoning(tmpl, jinja_caps.supports_tool_calls)
    |     |-- R1: compare_reasoning_presence()   — with/without reasoning_content field
    |     |-- R2: compare_thinking_enabled()     — enable_thinking=false vs true
    |     '-- R3: compare_reasoning_scope()      — reasoning+content vs reasoning+tools
    |           (only if supports_tool_calls)
    |
    |-- Phase 2: analyze_content(tmpl, reasoning)
    |     '-- C1: compares content-only vs tools output and content-only vs reasoning output
    |
    |-- Phase 3: analyze_tools(tmpl, jinja_caps, reasoning)
    |     (skipped entirely if !jinja_caps.supports_tool_calls)
    |     |
    |     |-- T1: analyze_tool_calls()           — no tools vs with tools; classifies format
    |     |         |-- JSON path → analyze_tool_call_format_json_native()
    |     |         '-- tag path → analyze_tool_call_format_non_json()
    |     |
    |     (if format != NONE and format != JSON_NATIVE:)
    |     |
    |     |-- T2: check_per_call_markers()       — 1 call vs 2 calls; moves section→per-call if needed
    |     |         (only if supports_parallel_tool_calls)
    |     |
    |     |-- T3: extract_function_markers()     — func_alpha vs func_beta; extracts name prefix/suffix/close
    |     |
    |     |-- T4: analyze_arguments()            — (TAG_WITH_TAGGED only)
    |     |         |-- A1: extract_argument_name_markers()   — arg_name_A vs arg_name_B
    |     |         '-- A2: extract_argument_value_markers()  — value "XXXX" vs "YYYY"
    |     |
    |     |-- T5: extract_argument_separator()   — 1 arg vs 2 args; finds separator between args
    |     |
    |     |-- T6: extract_args_markers()         — 0 args vs 1 arg; finds args container markers
    |     |
    |     '-- T7: extract_call_id_markers()      — call_id "call00001" vs "call99999"
    |
    '-- collect_preserved_tokens()               — union of all non-empty markers
    |
    '-- apply workarounds()                      — post-hoc patches for edge-case templates
    |
    v
autoparser (analysis result)
    |
    v
autoparser::peg_generator::generate_parser(tmpl, inputs, analysis)
    |-- analysis.build_parser(inputs)            — builds PEG parser arena
    |     |-- reasoning.build_parser(ctx)        — reasoning parser (mode-dependent)
    |     |-- content.build_parser(ctx)          — content parser (mode-dependent)
    |     '-- tools.build_parser(ctx)            — tool parser (dispatches by tool_format)
    |           |-- build_tool_parser_json_native()
    |           |-- build_tool_parser_tag_json()
    |           '-- build_tool_parser_tag_tagged()
    |
    |-- Build GBNF grammar (if tools present and trigger_marker non-empty)
    '-- Set grammar_triggers from section_start or per_call_start
    |
    v
common_chat_params (prompt, parser, grammar, triggers, preserved_tokens)

Entry Point

The auto-parser is invoked in common/chat.cpp:1280-1310 in common_chat_templates_apply_jinja. A few specialized templates are handled first (Ministral/Magistral Large 3, GPT-OSS with <|channel|>, Functionary v3.2 with >>>all), then the auto-parser handles everything else via autoparser::autoparser + peg_generator::generate_parser.

Algorithm Details

Core Mechanism: Differential Comparison

All analysis phases use the same factorized comparison function declared in common/chat-auto-parser-helpers.h:68:

compare_variants(tmpl, params_A, params_modifier)

This creates variant B by applying a modifier lambda to a copy of params_A, renders both through the template, and computes a diff_split (common/chat-auto-parser.h:28-37):

  • prefix — common prefix between A and B
  • suffix — common suffix between A and B
  • left — unique to variant A
  • right — unique to variant B

The diff is computed via calculate_diff_split(), which finds the longest-common-prefix and longest-common-suffix, then iteratively moves incomplete <...> or [...] markers from the prefix/suffix into left/right until stable (tag boundary fixing).

Text is segmentized into markers and non-marker fragments using segmentize_markers(), which splits on <...> and [...] boundaries.

Phase 1: Reasoning Analysis

R1 — compare_reasoning_presence(): Compares assistant message with vs without a reasoning_content field.

  • Searches diff.right (output with reasoning) for the reasoning content needle
  • Uses PEG parsers to find surrounding markers:
    • If both pre/post markers found in diff.rightTAG_BASED
    • If both found but post marker only in the full output B → TAG_BASED (template forces markers; handled via prefill)
    • If only post marker found → TAG_BASED (delimiter-style, empty start)
  • Sets reasoning.start and reasoning.end

R2 — compare_thinking_enabled(): Compares enable_thinking=false vs true with a generation prompt.

  • Detects template-added reasoning markers: enable_thinking=true adds a non-empty marker at the end of the prompt — sets reasoning.start, mode = TAG_BASED
  • Detects start+end pattern: enable_thinking=false produces both start+end markers; enable_thinking=true produces only start marker — both classified as TAG_BASED
  • Handles the reverse case: if both start and end are still empty, looks for a single-segment diff on each side to extract both markers
  • The reasoning prefill (markers added by the template) is later extracted in generate_parser() and prepended to model output before parsing

R3 — compare_reasoning_scope(): Compares assistant message with reasoning+text-content vs reasoning+tool-calls.

  • Only runs if jinja_caps.supports_tool_calls
  • Detects TOOLS_ONLY: reasoning content present in B (with tools) but not in A (with text content)
  • Extracts reasoning markers from the tool call output using PEG parsers

Phase 2: Content Analysis

C1: Two comparisons in the analyze_content constructor:

  • Comparison 1: content-only output vs tool-call output → diff_tools
  • Comparison 2: content-only output vs reasoning+empty-content output → diff_reasoning

Classification logic:

  • PLAIN: diff_tools.left equals the response string (content is the entire diff, no wrapper)
  • ALWAYS_WRAPPED: markers found surrounding the content text in pure_content → extracts start/end

Phase 3: Tool Call Analysis

T1 — analyze_tool_calls(): Compares no-tools vs with-tools output.

  • Extracts the tool call section as diff.right
  • Calls analyze_tool_call_format() which first strips reasoning markers from the haystack, then:
    • Calls in_json_haystack() for both function name and argument name needles
    • in_json_haystack() uses a PEG parser to check whether the needle appears in a JSON context (preceded by { or : with surrounding quotes)
    • If function name is in JSON → JSON_NATIVEanalyze_tool_call_format_json_native()
    • If function name not in JSON, arg name is in JSON → TAG_WITH_JSON
    • If neither in JSON → TAG_WITH_TAGGED
    • analyze_tool_call_format_json_native(): parses the JSON object, matches field values to needles to populate name_field, args_field, id_field, gen_id_field; detects tools_array_wrapped; extracts section_start/section_end
    • analyze_tool_call_format_non_json(): uses PEG parsers on the haystack to find up to two opening markers (section + per-call) then up to two closing markers

T2 — check_per_call_markers(): Compares 1 call vs 2 calls.

  • Computes a secondary diff of the second call portion vs the common suffix
  • If the second call content starts with section_start → the section marker is actually per-call → moves section_start/end to per_call_start/end and clears the section markers

T3 — extract_function_markers(): Compares function name FUN_FIRST vs FUN_SECOND (two different named functions).

  • Finds where the function name appears in diff.left
  • Extracts function.name_prefix from the common prefix up to the function marker, and function.name_suffix from after the name up to the next marker
  • Extends name_suffix into diff.suffix (to the first marker for TAG_WITH_TAGGED; to the first { or [ for TAG_WITH_JSON)
  • Extracts function.close from after the last argument value up to the per-call/section end marker

T4 — analyze_arguments() (TAG_WITH_TAGGED only):

  • A1 extract_argument_name_markers(): Compares arg_name_A vs arg_name_B (two different argument names).
    • Finds shared surrounding structure → arguments.name_prefix, arguments.name_suffix
  • A2 extract_argument_value_markers(): Compares argument value "XXXX" vs "YYYY" (same arg, different value).
    • Finds markers surrounding the value → arguments.value_prefix, arguments.value_suffix

T5 — extract_argument_separator(): Compares 1 argument vs 2 arguments (same function).

  • Uses until_common_prefix(diff.right, ARG_FIRST, ARG_SECOND) to find what separates the two argument blocks

T6 — extract_args_markers(): Compares 0 arguments vs 1 argument.

  • Uses until_common_prefix() and after_common_suffix() with the empty and single-arg JSON strings as anchors to find container markers (arguments.start, arguments.end)

T7 — extract_call_id_markers(): Compares call IDs "call00001" vs "call99999".

  • Determines whether function name appears in diff.prefix or diff.suffix to classify position:
    • Function name in prefix only → BETWEEN_FUNC_AND_ARGS or POST_ARGS (further distinguished by where { appears)
    • Function name in suffix only → PRE_FUNC_NAME
  • Extracts call_id.prefix and call_id.suffix markers around the call ID value
  • Clears per_call_end if it incorrectly incorporated the call ID suffix

Workarounds

A workaround array in common/chat-diff-analyzer.cpp applies post-hoc patches after analysis. Each workaround is a lambda that inspects the template source and overrides analysis results. Current workarounds:

  1. Old Qwen/DeepSeek thinking templates — source contains content.split('</think>'): sets reasoning.mode = TAG_BASED with <think>/</think> markers if no reasoning was detected
  2. Granite 3.3 — source contains specific "Write your thoughts" text: forces TAG_BASED reasoning with <think>/</think> and WRAPPED_WITH_REASONING content with <response>/</response>
  3. Cohere Command R+ — source contains <|CHATBOT_TOKEN|>: sets ALWAYS_WRAPPED content mode if no content start is already set
  4. Functionary 3.1 — source contains set has_code_interpreter: forces PLAIN content, specific per_call_start/end, clears preserved tokens to only keep Functionary-specific markers
  5. DeepSeek-R1-Distill-Qwen — source contains tool▁calls▁begin markers: overrides tool section/per-call markers with the correct Unicode block characters

Parser Building

Each analyzer struct (analyze_reasoning, analyze_content, analyze_tools) implements build_parser(parser_build_context&). They share a parser_build_context that carries the PEG builder, inference inputs, the pre-built reasoning parser, and a pointer to the content analyzer.

Reasoning Parser (analyze_reasoning::build_parser)

Mode Parser
Not extracting reasoning eps()
TAG_BASED or TOOLS_ONLY (non-empty start) optional(start + reasoning(until(end)) + end)
TAG_BASED or TOOLS_ONLY (empty start) optional(reasoning(until(end)) + end) — delimiter-style

Note: The start marker may be empty either because the analyzer detected delimiter-style reasoning, or because generate_parser() cleared a template artifact start marker (see Reasoning Prefill above). The reasoning prefill is prepended to model output before parsing.

Content Parser (analyze_content::build_parser)

Condition Parser
json_schema present reasoning + space() + content(schema(json(), "response-format", ...)) + end()
Tools present Dispatches to analyze_tools::build_parser()
ALWAYS_WRAPPED with reasoning reasoning + start + content(until(end)) + end + end()
ALWAYS_WRAPPED without reasoning content(until(start)) + start + content(until(end)) + end + end()
Default (PLAIN) reasoning + content(rest()) + end()

Tool Parsers (analyze_tools::build_parser)

Dispatches by format.mode:

build_tool_parser_json_native(): Calls p.standard_json_tools() which internally dispatches to:

  • build_json_tools_function_is_key() — function name is the JSON key: {"get_weather": {...}}
  • build_json_tools_nested_keys() — nested: {"function": {"name": "X", "arguments": {...}}}
  • build_json_tools_flat_keys() — flat: {"name": "X", "arguments": {...}}

Handles content wrappers, array wrapping (tools_array_wrapped), parallel calls, and parameter_order.

build_tool_parser_tag_json(): For each tool function:

tool_open(name_prefix + tool_name(literal(name)) + name_suffix) +
    call_id_section +
    tool_args(schema(json(), tool_schema))
  [+ function.close if non-empty]

Wrapped in per-call markers (with optional parallel call repetition) then optionally in section markers.

build_tool_parser_tag_tagged(): For each tool function, builds one parser per argument:

  • String types: tool_arg_string_value(schema(until(value_suffix), ...))
  • JSON types: tool_arg_json_value(schema(json(), ...))
  • Required args are plain; optional args wrapped in optional()
  • Arguments joined with space() between consecutive parsers

For closing: uses function.close if present; otherwise uses peek(per_call_end) to avoid premature close during partial streaming; falls back to tool_close(space()) to trigger mapper callbacks.

All three tool parsers return:

reasoning + optional(content(until(trigger_marker))) + tool_calls + end()

Python Dict Format

When format.uses_python_dicts is true (detected when single-quoted strings appear in JSON argument context), build_parser() pre-registers a json-string rule that accepts both single-quoted and double-quoted strings. This is done before any p.json() call so all JSON parsing inherits the flexible rule.

Mapper

common_chat_peg_mapper maps PEG parse results (AST nodes) into common_chat_msg structures. Key design:

  • Buffered arguments: Before tool_name is known, argument text goes to args_buffer; once the name is set, the buffer is flushed to current_tool->arguments
  • args_target(): Returns a reference to whichever destination is currently active (buffer or tool args), eliminating branching
  • closing_quote_pending: Tracks whether a closing " needs to be appended when a string argument value is finalized (for schema-declared string types in tagged format)
  • Quote normalization: Python-style quotes ('key': 'value') are converted to JSON ("key": "value")
  • Brace auto-closing: At tool close, unclosed { braces are closed automatically

Files

File Purpose
common/chat-auto-parser.h All analysis structs, enums, autoparser, peg_generator, templates_params
common/chat-auto-parser-generator.cpp Parser generator: generate_parser() and build_parser() methods
common/chat-diff-analyzer.cpp Differential analysis implementation and workarounds
common/chat-auto-parser-helpers.h/cpp calculate_diff_split(), segmentize_markers(),
compare_variants(), string helpers
common/chat-peg-parser.h/cpp common_chat_peg_builder, common_chat_peg_mapper, and helpers
common/chat.cpp Entry point: common_chat_templates_apply_jinja()
tools/parser/debug-template-parser.cpp Debug tool for template analysis
tools/parser/template-analysis.cpp Template analysis tool

Testing & Debugging

Debug Tools

Template Debugger: tools/parser/debug-template-parser.cpp

  • Usage: ./bin/llama-debug-template-parser path/to/template.jinja
  • Shows detected format, markers, generated parser, and GBNF grammar

Template Analysis: tools/parser/template-analysis.cpp

  • Usage: ./bin/llama-template-analysis path/to/template.jinja

Debug Logging: Enable with LLAMA_LOG_VERBOSITY=2

  • Shows detailed analysis steps, pattern extraction results, and generated parser structure

PEG Test Builder: Fluent API for creating test cases — see tests/test-chat.cpp:947-1043. Example usage:

auto tst = peg_tester("models/templates/Template.jinja");
tst.test("input text")
   .reasoning_format(COMMON_REASONING_FORMAT_AUTO)
   .tools({tool_json})
   .parallel_tool_calls(true)
   .enable_thinking(true)
   .expect(expected_message)
   .run();

Tested Templates

The following templates have active tests in tests/test-chat.cpp:

Template Format Notes
Ministral-3-14B-Reasoning Reasoning [THINK]...[/THINK] tags (specialized handler)
NVIDIA-Nemotron-3-Nano-30B TAG_WITH_TAGGED Reasoning + tools
CohereForAI Command-R7B JSON_NATIVE <|START_THINKING|>/<|START_RESPONSE|> markers
Google Gemma 2 2B Content only No tool support
Qwen-QwQ-32B Reasoning Forced-open thinking
NousResearch Hermes 2 Pro JSON_NATIVE <tool_call> wrapper
IBM Granite 3.3 JSON_NATIVE <think></think> + <response></response>
ByteDance Seed-OSS TAG_WITH_TAGGED Custom <seed:think> and <seed:tool_call> tags
Qwen3-Coder TAG_WITH_TAGGED XML-style tool format
DeepSeek V3.1 JSON_NATIVE Forced thinking mode
GLM-4.6 TAG_WITH_TAGGED <tool_call>name\n<arg_key>...<arg_value>... format
GLM-4.7-Flash TAG_WITH_TAGGED Updated GLM format
Kimi-K2-Thinking JSON_NATIVE Reasoning + JSON tools
Apertus-8B-Instruct JSON_NATIVE Function name as JSON key
MiniMax-M2 TAG_WITH_JSON XML invoke with JSON args
NVIDIA-Nemotron-Nano-v2 JSON_NATIVE <TOOLCALL> wrapper (nested)
CohereForAI Command-R Plus JSON_NATIVE Markdown code block format
Mistral-Nemo-Instruct-2407 JSON_NATIVE [TOOL_CALLS] wrapper with ID field
Functionary v3.1 TAG_WITH_JSON <function=X> format
Functionary v3.2 Specialized >>> recipient delimiter (dedicated handler)
Fireworks Firefunction v2 TAG_WITH_JSON Fireworks tool format
DeepSeek R1 Distill (Llama/Qwen) Reasoning Forced-open thinking
llama-cpp-deepseek-r1 Reasoning Forced-open thinking
Kimi-K2 / Kimi-K2-Instruct JSON_NATIVE JSON tools with special markers
Llama 3.1/3.2/3.3 JSON_NATIVE Standard Llama tool format
OpenAI GPT-OSS Specialized Channel-based (dedicated handler)
Apriel 1.5 JSON_NATIVE <tool_calls> wrapper with JSON array
Apriel 1.6 Thinker Reasoning Implicit reasoning start
Mistral Small 3.2 JSON_NATIVE [TOOL_CALLS]func[ARGS]{...} with call ID
Devstral JSON_NATIVE [TOOL_CALLS]func[ARGS]{...} without call ID
StepFun 3.5 Flash TAG_WITH_TAGGED <function=X><parameter=Y> format

Adding Support for New Templates

To support a new template format:

  1. If it follows standard patterns — The auto-parser should detect it automatically. Run llama-debug-template-parser to verify markers are correctly extracted.
  2. If differential analysis extracts incorrect markers — Add a workaround lambda to the workarounds vector in common/chat-diff-analyzer.cpp. Inspect the template source for a unique identifying substring.
  3. If it needs fundamentally different handling — Add a dedicated handler function in chat.cpp before the auto-parser block (as done for GPT-OSS, Functionary v3.2, and Ministral).

Edge Cases and Quirks

  1. Reasoning Prefill: See the reasoning_mode enum section above for the full description. Key detail: the generation prompt suffix is extracted via compare_variants(add_generation_prompt=false, add_generation_prompt=true) to avoid false positives from prior conversation turns.
  2. Per-Call vs Per-Section Markers: Some templates wrap each tool call individually (per_call_start/end); others wrap the entire section (section_start/end). T2 (check_per_call_markers()) disambiguates by checking if the second call in a two-call output starts with the section marker.
  3. Python Dict Format: The Seed template family uses single-quoted JSON ('key': 'value'). The uses_python_dicts flag causes the PEG builder to register a flexible json-string rule accepting both quote styles before any JSON rules are built.
  4. Tag Boundary Fixing: calculate_diff_split() iteratively adjusts prefix/suffix boundaries to avoid splitting <tag> or [marker] tokens, ensuring clean extraction.
  5. Call ID Side Effects: When a call ID is detected, per_call_end may have been incorrectly set to include the call ID suffix. T7 clears per_call_end in this case.
  6. Tool Analysis Gating: analyze_tools is only constructed (and all tool analysis phases run) when jinja_caps.supports_tool_calls is true. Within tool analysis, check_per_call_markers() (T2) only runs if jinja_caps.supports_parallel_tool_calls.
  7. analyze_arguments() Gating: Within tool analysis, A1 and A2 (argument name/value marker extraction) only run for TAG_WITH_TAGGED format. extract_argument_separator() and extract_args_markers() run for all non-JSON_NATIVE formats.