Update an existing customer's contact details by providing the customer ID and the fields to change: name, email, or phone.
Update fields on an existing customer.
| Name | Required | Description | Default |
|---|---|---|---|
| name | No | ||
| No | |||
| phone | No | ||
| customerId | Yes |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description 'Update fields' is consistent with these annotations and adds no extra behavioral context, such as whether it does a partial update or what happens to omitted fields. Since annotations carry the burden, a baseline 3 is appropriate.
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 is a single, concise sentence with no filler. It front-loads the core action and resource, and every word earns its place. There is no unnecessary detail or repetition.
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 mutation tool with no output schema and 0% schema description coverage, the description is too thin. It does not explain partial-update semantics, error behavior, or what happens to fields not provided. While the required parameter is in the schema, an agent would benefit from explicit guidance on how the update behaves. The description leaves significant gaps for correct invocation.
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%, and the description mentions no parameters at all. The property names (name, email, phone, customerId) are self-explanatory, but the description does not clarify that only customerId is required or that the other fields are optional updates. The description adds no value beyond the schema, failing to compensate for the coverage gap.
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 the verb 'Update' and the resource 'customer', specifying that it modifies an existing customer. This distinguishes it from create_customer and delete_customer, though it doesn't explicitly contrast with those siblings. The resource is unambiguous, so an agent can determine the tool's purpose.
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?
There is no guidance on when to use this tool versus alternatives like create_customer or delete_customer. The description implies it is for existing customers, but it does not explicitly state when to choose update over create, nor does it mention any prerequisites or limitations. An agent would have to infer usage from the sibling names.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.