update_contact

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

Annotations already indicate destructiveHint=true, so the update is mutating. The description adds 'Update' which is consistent but does not disclose any additional behavioral traits such as partial update behavior, validation errors, or side effects. With annotations covering the main safety profile, the description adds minimal extra transparency.

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 four sentences, front-loaded with the main purpose, then prerequisites, then fields explanation. Every sentence adds value without redundancy. No unnecessary detail or fluff.

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 presence of an output schema, return values need not be explained. The description covers the core operation, prerequisites, and the important fields parameter. It misses possible details about how optional parameters behave (e.g., whether omitted fields are left unchanged), but overall it is fairly complete for a mutation tool with good annotations.

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%, so the description must compensate. It explains the 'fields' parameter as a JSON object with an example, but does not explain other parameters (name, ddi, phone, email, username) beyond their names. This provides some added value but lacks detail for the majority of parameters.

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 contact by its ID' with a specific verb and resource. It distinguishes from sibling tools like create_contact, delete_contact, and get_contact by focusing on updating an existing contact identified by UUID. The additional guidance on the fields parameter reinforces the 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?

The description provides explicit prerequisites: 'Use list_contacts first to find the contact ID' and 'Call list_fields first to discover available field keys.' This guides when to use the tool. It does not explicitly state when not to use it or compare to alternatives, but the context is clear.

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