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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=true, idempotentHint=true), and the description adds a state precondition not present in structured data, which is genuine value. It does not explain why a rename is flagged destructive or what happens to the untouched field, leaving a small gap.

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?

A single front-loaded sentence that states the operation and its gating constraint with zero redundancy or 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?

For a no-output-schema mutation the description is serviceable but omits two things an agent needs: that title and genre are both optional yet at least one must be supplied (only songId is required), and any indication of what the destructiveHint implies for existing song data.

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 100%, including a fully enumerated genre list and the provenance of songId ('from list_songs or create_song'), so the schema carries the parameter burden. The description adds no format or constraint detail beyond it, which is the expected baseline.

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 and resource ('Changes the title or the genre of a song') and clearly distinguishes the mutation from siblings like create_song or list_songs. It does not, however, explicitly contrast itself with any sibling by name, so an agent must infer it is the only rename/edit path.

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?

Provides an explicit when-not condition: editing is disallowed 'while it is being mixed,' which is actionable gating guidance. No alternative tool is named for the blocked case, so the agent is left to guess what to do instead of waiting.

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