Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare the safety profile (readOnlyHint false, idempotentHint true, destructiveHint false). The description adds useful behavioral context — that it engraves from an in-memory string, that a preview PNG comes back for iteration, and that it is not the persistence path. It does not itself state that assets are written to a directory, but the schema and annotations cover that.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences, front-loaded with the core capability, then the iteration workflow, then the hand-off to the sibling. Zero filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present and 100% parameter coverage, the description need not restate outputs. It supplies the workflow and sibling routing an agent needs to pick this tool correctly, and nothing material is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and every parameter (crop, name, formats, preview, output_dir, include_dirs) is documented in the schema, so the baseline is 3. The description echoes the preview workflow but adds no syntax or format semantics beyond what the schema already provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Engrave LilyPond code') and immediately differentiates scope: inline code with no source file on disk. This cleanly separates it from the sibling engrave_file, which requires a .ly file.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit when-to-use ('iterating on a musical idea: engrave, read the preview PNG, adjust, repeat') and an explicit when-not-to + alternative ('For anything worth keeping, write a .ly file and use engrave_file instead'). This is textbook routing guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare non-read-only, idempotent, non-destructive, so the safety profile is covered. The description goes beyond them with failure behavior ('errors' carries LilyPond diagnostics including line numbers), crop semantics, and the preview PNG being attached inline — real behavioral context. It stops short of stating runtime cost or overwrite behavior of output_dir.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the purpose, then format-selection rationale, then failure behavior — every sentence carries distinct information with no filler or repetition. Sized appropriately for a tool with multiple output formats and layout-software considerations.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With a 7-parameter schema fully described and an output schema present, the description supplies exactly the missing layer: format tradeoffs and error reporting. An agent has everything needed to invoke it correctly without opening the schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3 and the schema already documents each parameter. The description still adds meaning not in the schema, notably that SVG glyphs are outlines for web use and the font-embedding distinction between PDF and EPS. It says nothing extra about name, output_dir, or include_dirs resolution beyond their schema text.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a concrete verb and resource ('Engrave a LilyPond (.ly) source file') and states the output class ('publication-quality music notation assets'), which is far more specific than the title alone. The phrase 'source file' implicitly separates it from the sibling engrave_code, but the distinction is never made explicit.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives strong, actionable guidance on which output format to choose and why (PDF for InDesign, SVG outlines for web, EPS for Ghostscript but not InDesign), plus the crop and preview conditions. It does not tell the agent when to prefer engrave_file over engrave_code or when to call lilypond_version, which is the one routing gap.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

readOnlyHint=true already tells the agent this is a safe read, and an output schema exists, so return format is covered. The description still adds a genuinely useful behavioral fact: the reported version is the one the server actually engraves with, which is what makes the compatibility check valid.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, zero filler, with the core identity of the tool front-loaded before the usage hint. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter read tool with an output schema and a readOnly annotation, the description covers everything an agent needs: what is reported and why to call it. No gaps remain.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so there is no parameter semantics to convey; the 4 baseline applies. Nothing in the description is needed to understand the (empty) input.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ('Report') and a precisely scoped resource ('the LilyPond version this server engraves with'), which is meaningfully narrower than just 'the LilyPond version'. It is inherently distinct from the engrave_* siblings, though it never names them explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Use it to pick the right \version header for new .ly files' gives a concrete triggering situation for calling the tool. There are no competing alternatives to disambiguate against, so no explicit exclusion is needed.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.