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

Annotations declare destructiveHint=true and idempotentHint=false, but the description adds real context beyond them: it is a partial update ("leaves the others as they are"), body_markdown wholesale replaces the body, and nothing is pushed to subscribers. That last point usefully bounds the blast radius implied by the destructive flag rather than contradicting it.

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?

Four short sentences, front-loaded with the action, then the update semantics, then the eligibility constraint, then the confirmation note. No sentence is redundant with another.

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?

For a 2-parameter mutation with full schema coverage and annotations, the description covers eligibility, partial-update behavior, and side effects. Only minor gaps remain, such as what the error response looks like or any field-level constraints on title/audience.

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 coverage is 100%, so the baseline is 3, but the description adds semantics the schema does not: changes are partial per key, and body_markdown replaces the entire body rather than appending. That is the one non-obvious behavior of the fields object and it is called out.

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 (Change) and resource (draft) and enumerates the mutable fields: title, subtitle, body, audience. That makes it easy to separate from create_draft, publish_post, and schedule_post without opening any 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?

"Drafts and scheduled posts only: a published post returns an error" is an explicit when-not condition, and the closing clause resolves the confirmation question for the agent. It stops short of naming a sibling alternative (e.g. unpublish_post then edit), so it is not a full 5.

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