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

Annotations already indicate a non-read-only, non-idempotent, non-destructive operation, but the description adds crucial context: the reply is additive yet reversible by deletion, and not idempotent with a clear consequence of double-posting on retry. It also discloses the auth requirement (PAGE token with pages_manage_engagement and MODERATE), which annotations do not cover. No contradiction with 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?

The description is three sentences, each earning its place: public visibility, sibling alternative, and idempotency/retry warning with auth. It is front-loaded with the core action and contains no filler or repetition.

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 write tool with 5 parameters and no output schema, the description covers purpose, visibility, alternative routing, retry behavior, reversibility, and authorization. The 100% schema coverage handles parameters, and the description supplies all operational context an agent needs to invoke 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 description coverage is 100%, so the schema carries the parameter meaning. The description adds slight value by clarifying the message is "written by you" and that comment_id is "Not a post ID," but these are marginal enhancements over an already fully documented schema, so the baseline 3 is appropriate.

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 opens with a specific verb and resource: "Post a PUBLIC reply under a comment — visible to everyone who can see the thread." It explicitly distinguishes itself from facebook_private_reply, making it immediately distinct from the closest sibling without needing to open its 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?

It gives an explicit alternative and condition: "For a private message to the commenter use facebook_private_reply instead." It also provides retry guidance (verify with facebook_list_comments before retrying) and states the required token and task, so the agent knows exactly when and how to use it.

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