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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds a genuinely useful operational fact not present in structured data — the 1-credit cost. It omits what happens on an invalid/suspended handle and does not explain that results may be cached.

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?

Two short sentences with the returned-data inventory front-loaded and the cost appended. The only waste is the redundant 'Profile.' opener.

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?

There is no output schema, and the description compensates by listing the returned fields; cost is disclosed and the identifier formats come from the schema. The remaining gap is caching/staleness behavior tied to cache_max_age, which an agent would want before spending a credit.

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?

The handle formats are documented entirely in the schema, so the description contributes nothing there. More importantly, cache_max_age has no schema description and the description never mentions caching at all, leaving a parameter completely unexplained across both sources.

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 second sentence names the resource (public profile for a Bluesky account) and enumerates the returned fields, which clearly separates it from bluesky_post and bluesky_userPosts. The leading word 'Profile.' merely restates the title and adds nothing, but the substance is specific and accurate.

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?

Usage is only implied: the field list signals 'use this when you need follower counts, bio, avatar, verification', which implicitly routes away from the post-oriented siblings. There is no explicit when-to-use, when-not-to-use, or named alternative.

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