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

Annotations already declare the mutation/idempotency profile, and the description adds real context on top: an optimistic-concurrency precondition ('at its expected revision') and a hard scope limit ('Never publishes'), neither of which is derivable from the schema. It still does not explain what a stale revision produces or why destructiveHint is true for a draft-only save, which is the one gap keeping this 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 short sentences, no filler, and the core action is front-loaded before the two constraints. Every clause carries distinct information (action, non-publishing scope, idempotent retry).

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?

Output schema exists so return values need not be described, and the annotations cover safety, leaving the description to carry the operational burden it mostly delivers (revision precondition, retry semantics, draft-only scope). However, for an 8-parameter mutation with a deeply nested settings object and 0% schema coverage, the description is too thin about what an edit replaces and how revision conflicts surface.

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% across 8 parameters including a large nested settings object with dozens of platform-specific fields. The description adds meaning for only two of them ('revision', 'idempotencyKey'); postId, content, settings, connectionId, mediaAssetId and mediaAssetIds receive no semantic guidance anywhere.

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?

Specific verb + resource: 'Edit an editable post ... and save it as a draft', plus a distinguishing scope constraint ('Never publishes'). That implicitly separates it from create_draft and the publishing paths (schedule_post, update_campaign_post), but no sibling is named explicitly, so differentiation is left to inference rather than stated.

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?

'Never publishes' is a useful when-not boundary and the idempotency-retry advice is operational guidance, but there is no statement of when to choose this over create_draft, update_campaign_post, validate_post, or schedule_post, nor prerequisites such as what makes a post 'editable'.

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