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

Adds substantial behavioral context beyond the annotations: it declares a WRITE operation, partial-update semantics ('send only the fields to change'), replacement behavior ('replaces the previous values of the fields you send'), and explicit field-level exclusions. This directly clarifies what is destructive and what is out of scope, consistent with the destructiveHint annotation.

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?

Very concise and front-loaded with the WRITE marker and core action. Each clause adds distinct value: update scope, partial-send rule, exclusions, replacement semantics, and endpoint. No wasted text.

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 19-parameter schema and rich annotations, the description covers the essential invocation and safety context. However, with no output schema, it does not describe what the tool returns after a successful update, leaving a minor contextual gap for an agent expecting a response payload.

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%, so the per-field descriptions already carry most parameter meaning. The description still adds a key usage rule: only send fields that should change, which is not expressed in the schema. It does not add field-specific details beyond the schema.

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 and resource: 'change fields of an existing customer'. Clearly distinguishes update from create, get, and list siblings. The write prefix and endpoint reinforce the action.

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?

Explains when to use it: to change fields of an existing customer, and specifies that only changed fields should be sent. It also excludes payment methods, balances, and status. However, it does not explicitly route to alternative tools such as create_customer or get_customer.

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