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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description adds value by clarifying the project-scoped behavior ('acts only on the explicit project_id') and the return payload ('returns the project identity with its result'). It also implies the operation is non-destructive by saying 'without re-adding it'. No contradictions with annotations; it complements them with scoping and return details.

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 compact yet information-dense. It front-loads the critical scope constraint ('PROJECT-SCOPED'), then states the purpose, usage examples, and parameter hints in logical order. Each sentence earns its place; no fluff. Could be slightly more structured (e.g., bullets) but remains efficient.

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 4 required parameters and no output schema, the description covers the key elements: project_id scope, id source, kind enum, and gain_db example. It mentions the return value ('returns the project identity with its result') but does not elaborate on the result structure or error conditions. For a relatively simple mutation tool, this is adequate, though a bit more detail on the return payload would improve completeness.

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 description coverage is only 25% (only project_id has a description). The description compensates by explaining kind ('music', 'sfx' or 'voiceover'), id (from get_edl), and gain_db (example '-12', implying decibels). It adds meaning beyond the bare schema, though units for gain_db are only implied, not explicitly 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 states a specific verb ('change'), a precise resource ('loudness of an EXISTING music, sound-effect or voiceover item'), and explicitly differentiates from adding items ('without re-adding it'). The phrase 'THE tool for' and concrete examples ('lower the music', 'make the narration quieter') make its purpose unmistakable and distinguish it from sibling tools like set_volume or add_music.

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 clearly indicates when to use the tool via colloquial scenarios and emphasizes it operates on existing items ('without re-adding it'). It also provides the source for the id parameter ('id from get_edl'). However, it does not explicitly name alternative tools (e.g., set_volume, set_master_loudness) or state when those should be preferred, leaving some ambiguity for edge cases.

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