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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds that this is a prerequisite lookup feeding create_post, but says nothing about caching, freshness, or that results are static reference data per platform.

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 sentences, both earning their place: the first enumerates the payload, the second gives the sequencing instruction. Front-loaded and waste-free.

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 usefully enumerates what is returned (limits, daily cap, media types, platformSettings schema), which is what an agent needs to know to build a create_post call. Missing only notes on freshness or whether results can be cached.

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 0%, but the single parameter is a self-documenting enum of nine platform names. The description only implies the parameter via 'for a given platform' and adds no format or value guidance beyond the schema's enum list.

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?

Specific verb ('Return') plus a concrete enumeration of the resource contents: character limits, daily post cap, supported media types, and the platformSettings schema. This clearly separates it from validate_post and get_post_status, though it overlaps somewhat with the sibling get_upload_limits, which is not addressed.

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 states the sequencing context: 'Call this before create_post to ensure inputs are valid.' That gives the agent a clear trigger condition. It does not, however, mention when NOT to use it or name the near-neighbor siblings (get_upload_limits, validate_post).

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