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

Annotations already declare idempotentHint=true and destructiveHint=false, so safety is covered; the description's one real contribution is the partial-update guarantee ('only the fields you pass are changed'), which is valuable. It says nothing about status transition validity (can POSTED be set directly?), whether scheduledFor:null clears a schedule, or what side effects scheduling triggers.

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 short sentences, front-loaded with the resource and the mutable field list, with zero filler. Appropriate size for a simple partial-update tool.

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?

A mutation tool with no output schema, no parameter descriptions, and only lightweight annotations receives too little support here: required id is unmentioned, the status enum's transition rules are undefined, and the interaction between status and scheduledFor (a SCHEDULED post needs a future date) is not described.

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%, so the description must compensate; it names four of five parameters (caption, schedule, timezone, status) but leaves `id` unexplained and renames `scheduledFor` as 'schedule'. With an enum on `status` and a nullable date-time, the description gives no meaning to the values or to null semantics.

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?

Names a specific verb (update) and resource (post) and enumerates the mutable fields, which cleanly separates it from create_post, delete_post, and get_post. It does not mention the required `id` parameter, so the definition is slightly incomplete about which post is targeted.

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?

There is no statement of when to use this versus retry_post or create_post, no preconditions (e.g., whether only DRAFT/FAILED posts are editable), and no error conditions. The only usage-adjacent signal is the partial-update note, which is behavioral rather than routing guidance.

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