Update an SMS Center contact by ID. Provide the contact ID and new phone number, plus optional name fields, to replace existing contact details.
Update (replace) an SMS Center contact by contact_id.
| Name | Required | Description | Default |
|---|---|---|---|
| last_name | No | Last name | |
| contact_id | Yes | Contact id | |
| first_name | No | First name | |
| display_name | No | Display name | |
| phone_number | Yes | Contact phone number |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry the behavioral transparency burden, but it only reveals that the operation is a 'replace'. It does not disclose whether omitted fields are cleared, whether the operation is irreversible, what permissions are needed, or what the response contains. This is minimal for a mutation tool.
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, front-loaded sentence with no filler. It conveys the core operation and key attribute immediately, making it easy to scan.
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 annotations and no output schema, the description is too sparse. It does not clarify replacement semantics for missing optional fields, error behavior, or any call prerequisites, so an agent may not be able to invoke it correctly without additional assumptions.
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 schema already documents all five parameters and their types. The description adds only the emphasis that the contact is located by contact_id, which is already in the schema. Baseline 3 is appropriate because the schema does the heavy lifting.
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 states a specific verb ('Update (replace)'), a resource ('SMS Center contact'), and the key identifier ('by contact_id'). This clearly distinguishes it from sibling tools like create_contact, delete_contact, and update_contact_list without requiring schema inspection.
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?
The phrase 'Update (replace) an SMS Center contact' implies the tool is for modifying an existing contact, but there is no explicit statement about when to use it versus alternatives like create_contact or delete_contact. No when-not-to-use or prerequisite guidance is provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.