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

With annotations already covering read/idempotent/open-world safety, the description still adds substantial non-obvious behavior: cost model (x402 USDC on Base, $0.002 per successful call), the payment-required failure path, the 50-item ceiling, and cursor pagination. These are exactly the traits an agent cannot infer from the schema or annotations.

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?

Purpose is front-loaded and the payment caveat is isolated in its own sentence; every clause carries information. The middle clause enumerating returned fields is dense, but it is informative rather than padded.

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?

No output schema exists, yet the description lists the fields returned, the maximum record count, and how pagination and payment errors behave, so an agent can plan both the call and the response handling. Nothing material is missing for a read-only feed tool.

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 3-baseline applies, but the description does add interpretive value: it explains that the result set contains original posts by default and that replies/reposts are opt-in via the filter, framing filter choice in terms of returned content. The limit ceiling and cursor behavior largely restate schema text.

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: 'monitor what a specific Bluesky account has posted recently', plus the returned payload shape (up to 50 posts with text, time, engagement counts, links). This clearly separates it from bluesky_search (keyword search) and bluesky_profile (account metadata) even though those siblings are never named.

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?

Gives a clear use case ('monitor what a specific account has posted recently') and practical invocation guidance for the paid flow ('call without payment to receive the PaymentRequired object'). It stops short of naming alternatives such as bluesky_search for keyword-based discovery, so there is context but no explicit exclusion.

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