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

Beyond the readOnly/openWorld annotations, the description discloses the auth requirement (prepaid API key) and the return shape ('compact, cited results, each item has a url'). It does not mention rate limits or error behavior on unsupported/unavailable posts, keeping it from 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?

Three short sentences, front-loaded with the core operation and the return format. The platform list partially duplicates the enum in the schema, which is the only real redundancy.

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?

With no output schema, the description earns its place by characterizing the return payload and the citation field. Auth prerequisites and supported platforms are covered; missing only failure modes and any guidance on obtaining a valid post ID.

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 coverage is 100%, so both parameters are already fully documented, including the ID-or-URL duality and the platform enum. The description adds no syntax, format, or normalization detail (e.g. how X/TikTok URLs are parsed), so the 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 names a specific resource and scope ('One post by ID or URL') plus the payload ('full text and metrics'), which clearly separates it from list-oriented siblings like search_posts or get_user_posts. It stops short of naming an alternative explicitly, so it is clear but not maximally differentiated.

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: the description states the supported platforms and the prepaid-key prerequisite, which tells an agent when the tool can be called. It never says when to prefer this over search_posts/get_user_posts, nor that a post ID must first be discovered via search.

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