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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds real behavioral context beyond that: missing, deleted, or blocked posts may be silently omitted by the public AppView, which an agent must know to avoid misreading incomplete results. It does not add auth or pagination detail, but the public scope is implied.

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?

Front-loads the action and scope in the first clause, then the omission caveat, then the alternatives. Two tight sentences with no filler, though the 1-25 detail repeats the schema rather than adding 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?

An output schema exists, so return-value detail is unnecessary, and the annotations carry the safety profile. The description supplies scope, caveats, and routing, which is sufficient to call the tool correctly; only minor gaps like pagination/result-set behavior remain.

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% for the single 'uris' parameter, and the schema already documents the 1-25 bound and the repeat-for-multiple behavior. The description largely restates this, so baseline 3 is appropriate with no meaningful added semantics.

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?

States a specific verb and resource ('Fetch public Bluesky post items') and pins the input domain ('1 to 25 at:// URIs'). It also names the sibling tools it is not (bluesky_author_feed, bluesky_post_thread, bluesky_search_actors), so an agent can distinguish it from the other bluesky_* tools without opening any schema.

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?

Explicit routing guidance: author timeline -> bluesky_author_feed, conversation -> bluesky_post_thread, actor discovery -> bluesky_search_actors. This covers when to use this tool versus the obvious alternatives, leaving nothing to inference.

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