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

Annotations already convey that this is a write operation and not destructive. The description adds valuable context beyond them by disclosing the 409 conflict for already-submitted applications and the required NOMADSTAYS_MCP_AGENT_TOKEN. It also mentions that validation rules match createStayApplication, providing additional behavioral expectations.

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?

The description consists of three sentences, each serving a distinct purpose: action and scope, usage guidance, and error/auth context. It is front-loaded with the primary purpose and contains no redundant information.

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?

Given the 25-parameter schema and no output schema, the description covers the essential operational aspects: what it updates, constraints (unsubmitted, 409), auth requirements, and validation inheritance. It does not describe success response or return values, which is a minor gap since there is no output schema, but the core behavior is well covered.

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 low (16%), so the description must compensate. It does so by clarifying partial-update semantics ('only pass the fields you're changing') and by stating 'same field set and validation rules as createStayApplication,' which directs the agent to that tool's schema for full field meanings. This is a reasonable compensation for the low inline coverage.

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?

The description clearly states 'Update any subset of fields on an existing, not-yet-submitted Stay Application' with a specific verb and resource. It distinguishes from siblings by emphasizing 'existing, not-yet-submitted' and referencing the same field set as createStayApplication, making it distinct from create and submit operations.

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?

Provides explicit conditions: use for existing applications that have not been submitted, and fails with 409 if already submitted. Also advises 'only pass the fields you're changing.' It references createStayApplication for field set/validation, but does not explicitly name alternatives like create or submit, so it lacks an explicit 'when to use vs other tools' statement.

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