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

Annotations cover the safety profile (readOnly=false, destructive=false, openWorld=false), and the description adds real context beyond them: upsert-in-place semantics, tenant scoping with no project arg, and the downstream binding consequence. The only friction is that 're-POSTing the same kitId updates it in place' reads as idempotent behavior while idempotentHint=false suggests repeated calls may have side effects; it is a mild tension rather than a hard contradiction, and no permission/auth requirements are stated.

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?

Front-loads the verb+resource and the upsert/update duality, then the workflow and binding path, so the important routing info comes first. It is dense with parentheticals and REST asides, but nearly every clause carries actionable meaning.

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?

An output schema exists so return values need not be explained, and the description supplies the workflow, upsert behavior, and tenant scoping needed to select and call the tool correctly. The remaining gap is partial-update semantics (replace vs merge on re-POST) and auth expectations, which are left unstated for a large mutation.

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% on a single deeply nested body object, so the schema already carries the field semantics and the baseline is 3. The description only adds a high-level 'fonts/colors/logo' summary, and notably omits whether a re-POST replaces or merges the rest of the kit, which matters for an upsert.

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?

Starts with a specific verb+resource ('Create or UPSERT a brand kit') and immediately defines its scope ('Sets fonts/colors/logo', 'Tenant-scoped'). The parenthetical that re-POSTing the same kitId is 'also the brand-kit UPDATE path' tells an agent this single tool owns both create and update, distinguishing it from any assumed sibling updater.

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 an explicit workflow position ('brand step 0'), the exact downstream alternatives for binding ('pass its kitId as brandKitId to create_project, or attach it to an existing project via update_project'), and the consequence of skipping that step ('create_render produces UNBRANDED output'). This is genuine when-and-how guidance rather than restated purpose.

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