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

The description discloses billing ('Billed $0.003 per request') and the exclusivity requirement ('exactly one of url or post_id'), which are useful behavioral details. However, with no annotations provided, the description carries the full burden. It does not mention pagination, rate limits, or what happens if both parameters are provided. The billing disclosure is a positive, but the lack of pagination/error behavior leaves a gap.

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?

The description is two sentences with no wasted words. It front-loads the core action, then adds the billing and parameter constraint. Every sentence 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 read tool with three well-documented parameters, the description is mostly complete. However, there is no output schema and no mention of pagination or result structure, which an agent might need to know for a comments endpoint. The billing and exclusivity details are helpful, but the lack of pagination/response info keeps this at a 3.

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%, so the schema already documents all three parameters thoroughly. The description adds the 'exactly one of' constraint, which is valuable, and mentions the sentiment surcharge. However, it does not add much beyond the schema's own parameter descriptions. Baseline 3 is appropriate because the schema does the heavy lifting.

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 and resource: 'Get the replies to a Bluesky post.' This clearly distinguishes it from sibling tools like bluesky_post_likes, bluesky_post_quotes, and bluesky_post_reposts, which retrieve different engagement data. It could be slightly stronger by explicitly naming a sibling, but the resource and action are 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?

The description provides a clear usage constraint: 'Provide exactly one of url or post_id.' This tells the agent how to invoke the tool correctly. It does not explicitly state when to choose this over alternatives, but the tool name and description make the use case obvious (fetching comments/replies for a Bluesky post).

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