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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-structured context: results are ten per page, pagination is cursor-based, the post must be public, and the call costs 1 credit. The opening 'Replies to a comment' is momentarily ambiguous (posting vs. retrieving) but is resolved by the per-page detail.

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?

Four short sentences, front-loaded with the action, followed by prerequisites, pagination, and cost. Minor redundancy in restating cursor as pagination.cursor, but nothing wasteful.

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 carries return-shape burden and does so adequately by stating page size and cursor reuse. The only gap is cache_max_age, which is unexplained in both schema and description, and no explicit statement of what a reply record contains.

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 75%, so most parameters are already documented. The description adds provenance for comment_id (any `id` from /v1/facebook/post-comments) which is real value beyond 'Numeric comment id', but it says nothing about cache_max_age, the one parameter undocumented in the schema.

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 ('Replies to a comment ... under one comment on a public Facebook post'), which is enough for an agent to identify the operation. It implicitly separates itself from facebook_postComments by pointing at that endpoint as the id source, though it never names the sibling outright.

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 a concrete prerequisite workflow: obtain the comment id from /v1/facebook/post-comments, then call this tool, then follow pagination.cursor. It does not explicitly state exclusions (e.g., private posts) beyond 'public Facebook post', but the usage context is clear.

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