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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds value beyond that with "FREE" (cost signal) and "Verified" (provenance/currency of the limits), which materially affects whether an agent trusts the numbers. It doesn't mention caching or versioning of the specs, keeping it out of 5 territory.

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, no redundancy, with the cost note and scope front-loaded before the usage instruction. Every clause 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?

With no output schema, the description compensates by enumerating the returned fields, so an agent knows what to expect from the call. For a zero-required-parameter, read-only lookup tool, nothing needed for correct invocation is missing.

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% and the sole parameter's description already states "Target platforms (default: all 14)". The description's "14 social platforms" reinforces but does not add semantics such as case sensitivity or behavior with an empty array, 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 (per-platform specs) and enumerates exactly what is returned: character/title limits, hashtag caps, image ratios and pixel sizes, link behavior, publishing method, across 14 named platforms. That specificity lets an agent separate it from omnipost_validate (which checks content) and omnipost_publish (which posts) without opening a 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?

"Use before writing any social post" gives a clear triggering condition and sequencing advice. It stops short of naming an alternative or exclusion — e.g. it doesn't say to prefer omnipost_validate for checking already-drafted copy — so a 4 rather than a 5.

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