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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds non-obvious cost semantics (1 scraper credit per successful call), which is genuinely useful context an agent cannot get from structured fields. It stops short of describing return shape or pagination limits for top-level items vs comments.

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?

Three short sentences: purpose, cost, and workflow. Front-loaded with the action and resource, then the cost, then usage. 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, no-output-schema tool this covers the essentials: what it returns conceptually, its cost, and its place in the workflow. The one gap is not clarifying the relationship between maxItems and maxComments or the shape of the returned thread, which matters for a comment-fetching tool with two pagination-style params.

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 url, maxItems, and maxComments are already documented with defaults. The description adds no parameter-level detail beyond reinforcing that url is a single post URL. Baseline 3 applies when the schema does the heavy lifting.

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+resource (fetch comments/replies for a single X post URL) with clear scope limited to one post. An agent can distinguish this from get_social_post (the post itself) and search_social (discovery) without opening any 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?

Explicitly names the prerequisite workflow: find a post via search_social (platform "x"), then use this tool to read its discussion thread. It supplies both when-to-use and the alternative that precedes it, leaving nothing to inference.

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