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

With annotations only declaring safety/idempotency flags, the description carries the important behavioral burden and does it well: partial vs. exhausted collection, the fact that hasMore=false does not prove completeness, that exhausted means pagination ended rather than hidden comments/replies being captured, and that conclusions must be scoped to returned comments. This is material operational context an agent could not infer from the structured fields.

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 in one sentence, followed by tightly packed caveats about result interpretation. Every sentence carries information, though the three consecutive incompleteness caveats could be consolidated slightly.

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 paginated collection tool with no output schema, the description names the key result fields (collectionStatus, stopReason, hasMore) and how to interpret them, which is exactly the gap the schema cannot fill. Missing are auth/rate-limit expectations and the shape of individual comment objects, but nothing essential to correct invocation is absent.

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% (url, limit, cursor, sortBy all documented), so the baseline is 3. The description adds only indirect meaning — that a cursor is a "safe cursor" and that stopping is not evidence of completeness — without clarifying limit or sortBy behavior beyond 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 first sentence names a specific verb and resource ("List comments on an Instagram post or reel") and its Instagram scope implicitly separates it from the facebook_comments sibling. It stops short of an explicit contrast with the nearest alternative, but the purpose is unambiguous and front-loaded.

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?

"Check collectionStatus ... and stopReason before analysis" gives real guidance on how to consume results, but there is no statement of when to choose this tool over siblings (e.g. facebook_comments or instagram_stats) and no prerequisite/auth context. Usage is implied rather than spelled out.

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