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

Annotations already mark readOnlyHint=false and destructiveHint=false, so the mutation nature is known. The description adds valuable context: it preserves position, level, and fit, and it returns the project identity with the result. This goes beyond the annotations and informs the agent of key side effects. No contradiction exists.

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 and every sentence earns its place: scope, action, use case, and parameter sourcing. It is front-loaded with the project scope and avoids redundant phrasing. No wasted words.

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 3-parameter mutation with no output schema, the description covers the essential aspects: scope, action, preservation behavior, and return. It lacks explicit error handling or edge-case guidance, but these are often unnecessary for a straightforward swap. The description is adequate for an agent to call it correctly.

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 33% (project_id has a description). The description compensates partially by specifying sources: 'id from get_edl' and 'storage_key as for add_music', but it does not define the semantic meaning of id (e.g., identifies the music item to swap) or storage_key (e.g., new track key). The sourcing hints help but leave some ambiguity, so a mid-range score is appropriate.

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 uses a specific verb ('Replace') and resource ('the TRACK of an existing music item'), and adds a clear scope ('PROJECT-SCOPED') that distinguishes it from generic operations. It also explicitly frames the use case ('THE tool for 'use a different song' / 'try something more upbeat''), which differentiates it from siblings like add_music or remove_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?

The description clearly states when to use the tool: 'Replace the TRACK of an existing music item' and 'THE tool for 'use a different song' / 'try something more upbeat''. It also provides parameter sourcing guidance ('id from get_edl; storage_key as for add_music'), which hints at alternatives (add_music) but doesn't explicitly say when not to use this tool. That prevents a 5, but the context is strong.

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