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

Annotations already declare readOnlyHint and openWorldHint, and the description adds genuine behavioral detail beyond them: ordering (newest first), the returned fields, the pagination limitation ('no cursor'), and a cost of 3 credits. This is useful context that structured fields do not carry, though it omits auth/prerequisite notes.

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, followed by return fields, pagination constraint, and cost. Three compact sentences with no filler; slightly terse but 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 read-only, 2-param tool with a fully documented schema and no output schema, the description covers ordering, page semantics, return content, and cost. The only meaningful gap is not clarifying the boundary with instagram_comment_replies, but overall it is complete enough to invoke 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 already documents url and shortcode (including the 'pass this or shortcode' mutual option). The description adds no syntax or format meaning beyond the schema, so the baseline of 3 applies.

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?

States a specific verb and resource ('Get comments on an Instagram post') and enumerates the returned fields. It does not, however, name or distinguish itself from the sibling instagram_comment_replies, so an agent must infer that replies are fetched elsewhere. Clear but lacks sibling differentiation.

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 implies usage by noting it returns 'one page of the most recent comments' and that there is 'no cursor: one page per call,' which tells the agent pagination is not available. However, it never states when to prefer this tool over instagram_comment_replies or instagram_post, nor any exclusions.

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