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

Annotations declare readOnlyHint=false, destructiveHint=false, idempotentHint=true, so the safety profile is already known. The description adds valuable context: it reports design_mode, generated links expire after 2 hours, and provides an acceptable-use URL. It does not cover error behavior or rate limits, but these additions go beyond the 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 three sentences, front-loaded with the primary use case. The second sentence gives actionable recipe guidance. The third packs reporting and link expiry efficiently. Slightly dense but every sentence contributes; no redundancy.

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 7 parameters, nested objects, enums, and no output schema, the description covers the main purpose, usage, recipe tailoring, and key behavioral facts (design_mode, link expiry). It references 'describe' for deeper details on recipes and instruments. It is complete enough for an agent to invoke correctly, though it omits specifics about revise, zip, or format parameters that are covered in 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 description coverage is 86%, so most parameters are well-documented in the schema. The description adds semantic guidance: recipes are starting points, and pitch, bright, dur, or seed should be tailored per interaction. It also clarifies the instrument+play pattern for custom instruments, providing meaning beyond the structured fields.

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 purpose: generating UI or game sound effects (up to 16 per call) and auditioning custom instruments. It distinguishes from generic music generation ('song' sibling) by focusing on UI effects, but does not explicitly name or contrast with siblings like 'song'. Clear but lacking explicit sibling differentiation.

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 opening sentence gives a clear 'when to use' context: 'when the user wants UI or game sound effects or to hear a custom instrument.' It also advises that recipes are starting points and to tailor parameters per interaction. No when-not-to-use or alternatives are mentioned, but the usage context is clear and actionable.

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