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

With no annotations, the description carries the full burden of behavioral disclosure. It does add useful behavior context: the per-request cost ('Billed $0.003 per request') and the exclusivity requirement ('Provide exactly one of username or url'). However, it does not disclose potential error conditions, rate limits, data freshness, or whether the operation is read-only, leaving meaningful gaps.

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 sentences with no fluff: the first states the core operation and accepted identifiers, the second states cost and input constraint. The most important information is front-loaded, and every clause earns its place.

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 simple two-parameter read tool with no output schema and no annotations, the description gives enough to invoke correctly: what it returns ('full profile'), how to specify inputs, and cost. It lacks error-handling and output-format details, but these are minor for a straightforward profile fetch.

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, but the description adds meaningful semantic constraints beyond the schema. The schema lists both parameters as optional, while the description explicitly requires exactly one of them, and clarifies that the username parameter can be a handle, DID, or with/without leading '@'—the latter echoed in the schema but the exclusivity rule is new.

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 states a specific verb ('Get'), resource ('a Bluesky user's full profile'), and input methods ('by handle, DID, or profile URL'). It clearly distinguishes this from sibling tools like bluesky_user_posts or bluesky_user_followers, which target different aspects of a user's data. The platform and scope are immediately unambiguous.

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?

There is no guidance on when to prefer this tool over alternatives such as search_bluesky_users or bluesky_user_followers. It does not mention when not to use it or name sibling tools. The only usage instruction—'Provide exactly one of username or url'—is about input constraints, not tool selection, so the tool-choice guidance is effectively absent.

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