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

Annotations indicate readOnlyHint=false, destructiveHint=false, idempotentHint=true. The description adds behavior beyond these: it explains that omitted fields are untouched, details the two duck modes, and mentions it returns the project identity. No contradictions with annotations.

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?

The description is ~150 words and front-loaded with the project scope. Each sentence adds value: scope, action, examples, duck_mode semantics, and alternatives. It is structured and readable without excessive verbosity.

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?

Given 10 parameters and no output schema, the description covers the main behavioral aspects: it states return value (project identity), explains duck modes, and clarifies that omitted fields are preserved. Gaps remain around offset_s and units, but overall it is adequate for a non-destructive, idempotent edit tool.

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?

With only 10% schema coverage, the description must compensate. It explains several parameters implicitly via examples (start, end, loop, duck, fade_out) and explicitly describes duck_mode. However, parameters like offset_s, fade_in_s, and id are not explained, and units for numeric parameters are not stated.

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 clearly states the tool modifies existing music in place, with examples like 'start the music later' and 'fade it out'. It distinguishes itself from adding/removing music and from loudness adjustment via set_audio_gain, making its purpose unambiguous.

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?

Explicitly advises using this instead of remove+re-add (which loses settings) and directs loudness tasks to set_audio_gain. It also notes that omitted fields are left alone, giving clear context for when to use the tool.

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