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

With no annotations, the description carries the full burden and does well: it discloses partial-update semantics, slug immutability and the rename workaround, and that changes take effect immediately. It omits permission/auth requirements and any rollback or validation-failure behavior, which keeps it out of 5 territory.

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 tight clauses, front-loaded with the action and mutation semantics, then the constraint, then the rule. No filler. Slightly compressed, but every sentence adds information an agent needs.

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 12-parameter mutation tool with no annotations, it covers the critical facts: patch semantics, immutable identifier, immediate effect, and a required pre-read doc. An output schema exists so return values need not be described. Auth/permission expectations and validation failure behavior are the remaining gaps.

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 only 42% across 12 parameters, so the schema leaves roughly half the fields undocumented. The description compensates for the most important semantic (partial/patch behavior and slug immutability) but does not explain the remaining fields such as public, supports, taxonomies, hierarchical or menuPosition.

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 ('Update a custom post type'), scoped to types 'Fabrement created'. It is distinguishable from the create/delete post-type siblings by the verb alone, though it never names them. Clear purpose, but no explicit sibling differentiation beyond the verb.

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 concrete operating instructions: send only what changes, the slug identifies the resource, and renaming requires delete + create. It also names a prerequisite (get-skill-doc content-model-contract) before the first call. It does not explicitly contrast with create-post-type/delete-post-type beyond the rename note.

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