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

Annotations already cover the safety profile (readOnly, idempotent, not open-world), so the bar is lower, and the description still adds real context: the full status lifecycle (draft, scheduled, publishing, posted, failed) and the fact that once published each platform result carries either a link or an error. It does not mention pagination, auth, or rate limits, so it stops 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?

Purpose is front-loaded and the field enumeration and routing guidance are packed into two dense sentences with little waste. The field list is long, but each item earns its place because there is no output schema to carry that information.

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 carries the return-shape burden and does so: payload fields, per-platform caption overrides, status enumeration, and the published-result link-or-error shape. Combined with the routing guidance and annotation-covered safety, the agent has everything needed to call it correctly.

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 single postId parameter is already fully documented in the schema, including its source tools and dash tolerance. The description only restates 'by id' and adds no syntax or format detail beyond the schema, 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?

States a specific verb and resource ('Fetch one post by id') and immediately enumerates what that post contains, so the agent knows the payload before opening the schema. It is clearly distinguishable from list_posts (many) and get_performance (metrics), both of which it names.

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?

Gives three concrete when-to-use triggers – confirming what schedule_post/update_post saved, diagnosing a failure, and pre-checking before cancel_post – each tied to a sibling tool. It also routes the agent to list_posts for bulk retrieval and get_performance for metrics, so alternatives are explicit rather than inferred.

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