Update Contact

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

With no annotations, the description carries the behavioral disclosure. It explains the permission requirement, the partial-update semantics, and that it applies to the signed-in user's mailbox. It does not detail return values or error behavior, but the essential mutation behavior is disclosed.

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 two concise sentences plus a compact Chinese intent line. It front-loads the purpose, adds a critical usage guideline, and includes the permission note without unnecessary 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?

The description, combined with the fully documented schema, gives enough context for correct invocation. It covers permission, scope, and partial-update semantics. It lacks output/error details but this is acceptable given no output schema and the tool's relative simplicity.

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 coverage is 100%, so the baseline is 3. The description adds value by stating that only the fields to change need to be provided, which clarifies the optionality and partial-update behavior beyond what the schema's individual field descriptions offer.

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 tool updates a mailbox contact for the signed-in user, using a specific verb and resource. It distinguishes from sibling tools like contacts_create and contacts_delete, and explicitly notes partial updates with 'Provide only the fields to change.'

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?

Clearly indicates this is for updating an existing contact and mentions the required delegate permission (Contacts.ReadWrite). It does not explicitly name alternatives or exclusions, but the context is clear enough for an agent to select this tool over creation/deletion commands.

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