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

Annotations already declare this as read-only, idempotent, and non-destructive, providing the safety profile. The description adds that it returns display name, bio, counts, avatar, and verification status, but since an output schema exists, this is somewhat redundant. It does not disclose error behavior or rate limits, but for a simple read-only lookup with strong annotations, a 3 is appropriate.

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 two sentences, front-loaded with the action and resource, includes an example handle, and summarizes return fields. Every sentence adds value, with no filler or repetition of annotation data.

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 one-parameter read-only tool with rich annotations and an output schema, the description is fully adequate. It covers what the tool does, how to invoke it (by handle), and what to expect in the response. No additional context is necessary for correct selection and invocation.

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 description does not add meaning beyond what the schema already provides. The handle format and example are present both in the schema description and the schema examples. The description reinforces the example but introduces no new semantic detail, matching the baseline for well-documented schemas.

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 clearly states the tool's function: 'Look up a Bluesky user's profile by handle' with a specific resource (profile) and scope (by handle). It distinguishes from siblings like get_followers/get_follows by listing return fields (display name, bio, counts, avatar, verification status), which is unique to profile lookup.

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 provides clear context: use this tool to look up a profile by handle. It implies the appropriate use case for retrieving profile details, though it does not explicitly mention alternatives or exclusions. Given the sibling list, a direct comparison would have earned a 5, but the absence of explicit 'when not to use' guidance keeps it at 4.

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