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

Annotations already cover read-only and open-world. The description adds genuinely non-obvious behavioral facts the annotations don't: results are limited to public posts, ordering is newest-first, and each call consumes 1 credit. It does not disclose result volume limits or pagination mechanics, keeping it below a 5.

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, front-loaded sentences with no filler. The opening 'Search posts.' largely restates the title, making one sentence weakly redundant, but the remaining two carry real information.

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, so the description should describe what comes back, but it only mentions ordering. It also leaves cache_max_age unexplained. Adequate for a 3-parameter search tool, but not complete enough for a 4.

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?

Coverage is 67%: query and cursor are described in the schema, cache_max_age is not. The description adds no parameter detail beyond a hint that ordering is newest-first, so it does not compensate for the uncovered parameter. 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?

Specific verb+resource ('Search posts') scoped to 'Public Bluesky posts matching a keyword', which implicitly separates it from sibling lookups like bluesky_userPosts or bluesky_post (which fetch by user or by post). The keyword-vs-user distinction is inferable but never stated outright, so it stops short of a 5.

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?

'matching a keyword, newest first' and 'Costs 1 credit' imply the search use case and a cost budget, but there is no explicit statement of when to prefer this over bluesky_userPosts or the many other *_search siblings, and no prerequisites or exclusions.

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