update_contact

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

No annotations are provided, so the description must carry the transparency burden. It clearly discloses the key behavioral trait of partial update ('Only the fields you provide will be updated; other fields remain unchanged'), which is essential for safe invocation. It does not mention permissions or error handling, but the core non-destructive nature is well communicated.

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 exceptionally concise, front-loaded with the action, and every word adds value. It conveys both the purpose and the crucial partial-update behavior in just two short sentences, with no redundancy or filler.

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 tool with 10 parameters but no output schema, the description plus the fully documented schema provide enough information for an agent to invoke it correctly. The partial-update semantics are the most important contextual detail and are clearly stated. Minor gaps include no mention of return value or not-found error behavior, but these do not impede 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 100%, providing full parameter documentation and a baseline of 3. The description adds value by explaining that only provided fields are updated, which clarifies that all optional parameters are patch-style. This semantic context goes beyond simply listing 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 an existing contact's information' with a specific verb and resource, unambiguously distinguishing it from sibling tools like create_contact, get_contact, and delete_contact. The term 'existing' also sets it apart as a modification operation.

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 implies usage when the agent needs to modify an existing contact, but it does not explicitly state when to use this tool versus create_contact or get_contact, nor does it provide exclusions or alternatives. The word 'existing' hints at prerequisites but lacks explicit guidance.

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