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 new behavioral context beyond the annotations: the 1-scraper-credit cost per successful call and the fact that replies/comments are returned where available. It omits failure modes, rate limits, and auth/prerequisite details, keeping it short of a 5.

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 tightly written sentences with zero filler; the core action and scope come first, with the cost caveat appended where it belongs. Nothing redundant with the schema or annotations.

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 fetch tool with up to two well-documented parameters and no output schema, the description covers what is retrieved (full content plus replies/comments) and the per-call cost. It is nearly complete; only edge-case behavior (private, deleted, or unsupported URLs) is left unstated.

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 parameters (url and platform with its enum and default) are already fully documented by the schema. The description adds only the constraint that the post must be public and referenced by its URL, which is marginally beyond the schema. Baseline 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?

The description gives a specific verb (fetch), resource (a single public post), the supported platforms (Reddit, X, LinkedIn), and the input form (by URL), plus the useful scope note that replies/comments are included where available. It is clearly distinct from search_social (search) and scrape_url (generic), though it never names a sibling to route the agent explicitly.

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?

Usage is only implied: an agent can infer it should be used when it already has a specific public post URL. There is no explicit when-to-use vs. alternatives guidance, no statement of when not to use it (e.g., private/deleted posts), and no routing to search_social for discovery.

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