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 the meaningful cost signal '(1 credit)', but says nothing about pagination behavior despite offering a cursor parameter, or about how many comments are returned per page.

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 short fragments with the scope constraint front-loaded and no filler; the credit cost is appended cleanly. It is efficient, though it borders on under-specified for a tool with pagination.

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 annotations and no output schema, this is minimally adequate. An agent would still want to know that the cursor enables paging and whether replies are excluded, which the description leaves to inference.

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 both url and cursor are already documented in the schema, and the description adds no format or syntax detail beyond them. Baseline 3 applies since the schema carries the parameter burden.

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 names the specific resource (comments) and its scope (top-level only, on a Facebook post or video), which lets an agent distinguish it from the facebook_comment_replies sibling. It lacks an explicit verb such as 'list' or 'fetch', but the intent is 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 word 'top-level' implicitly routes the agent away from facebook_comment_replies, but that alternative is never named and no when-to-use or when-not-to-use condition is stated. Usage is inferable rather than explicit.

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