preview_post

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered structurally. The description still adds real value beyond that: it discloses the return payload's contents and, importantly, rules out an expectation an agent would plausibly have — it does not return screenshots, only structured data plus a dashboard link. It does not discuss permissions or freshness/caching of the preview, which keeps 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 sentences, front-loaded with the core behavior, then the when-to-use trigger, then the return-format caveat. No filler and no repetition of 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?

With no output schema, the description takes on the job of explaining what comes back, and it does: platform-resolved body, media, character counts, link behavior, warnings, plus a dashboard link and the explicit absence of screenshots. For a single-parameter read-only tool, nothing an agent needs to invoke it correctly 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?

There is a single parameter (id) with 100% schema description coverage ('Post ID to preview'), so the schema carries the meaning. The description says nothing additional about the id — e.g. whether draft, scheduled and published posts are all valid inputs — so the baseline of 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?

States a specific verb and resource: shows exactly what each platform will receive for a post, and enumerates the resolution it performs (body after platformContent overrides, attachments after platformMedia overrides, character count vs limit, link clickability, warnings). This clearly separates it from siblings like get_post or list_posts, which return stored data rather than platform-resolved previews.

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 says to use it BEFORE scheduling or publishing and calls out the high-risk cases (carousels, videos, multi-platform posts). It stops short of naming the alternative tool to use instead for other needs, or stating when a preview is unnecessary, but the timing guidance is unambiguous.

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