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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely useful context beyond the schema: the exact billing rate ($0.003/request) and the sentiment surcharge, plus what fields come back. Return format specifics like pagination are not addressed, but this is a single-item fetch so that gap is minor.

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 compact sentences: identification rule first, then return contents, then cost. Every clause carries information an agent needs; nothing is repeated from the schema verbatim.

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?

With no output schema, the description compensates by enumerating the returned fields (text, author, date, engagement metrics, media, link card, quoted post). Combined with the cost and the param rule, an agent has everything needed to call it correctly.

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 coverage is 100%, so the baseline is 3. The description adds the mutual-exclusivity rule ('provide exactly one' of url/post_id) which the schema itself does not state, and surfaces get_sentiment's effect, earning credit above baseline.

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 ('Get') and resource ('one Bluesky post') with a clear identification mechanism (URL or AT URI). An agent can distinguish this from siblings like bluesky_post_comments, bluesky_post_likes, and search_bluesky 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?

The 'provide exactly one' of url or post_id constraint is an explicit usage rule. However, it names no alternatives or when-not conditions (e.g., when to use this vs. search_bluesky or batch_requests), so guidance is clear but incomplete.

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