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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered by structured data. The description adds genuinely non-annotated context: a prerequisite (the user must have chosen to keep progress) and an implicit dependency on a token issued by keep_progress. It does not describe the shape of the response, which is a minor remaining 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?

Three short sentences, front-loaded with the positive trigger before the exclusions, and every clause carries routing or safety information. Nothing repeats the name or the annotations.

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 read-only, single-optional-parameter tool with no output schema, the description covers the trigger, the gating prerequisite and the content returned, which is enough to call it correctly. The only omission is any indication of response shape or empty-state behavior when the user has no recorded progress.

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%, and the single 'tap' parameter is fully documented in the schema, including its origin in keep_progress and the empty-string default. The description reinforces the precondition for that token but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 names the concrete data the tool surfaces — days listened this month, sessions played, badges — so an agent knows it is a read of the user's own progress summary rather than a generic account call. It stops short of a crisp verb+resource framing and does not explicitly distinguish itself from the my_badges sibling that appears to overlap on badge data.

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 gives an explicit trigger ('when the user asks how many days they listened this month...') plus two hard exclusions: not for medical/emergency/crisis questions, and not for users who did not opt into keeping progress. That is a clear when-to-use / when-not-to-use contract that an agent can route on without inference.

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