Add a contact

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

Annotations already mark this as a non-read-only, non-idempotent, non-destructive write. The description adds useful behavioral context beyond that: the server generates UID and file name, and the vCard version is resolved based on the address book. No contradiction with annotations.

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?

Two concise, front-loaded sentences with no filler. The first states the purpose; the second adds meaningful behavioral detail about UID generation and vCard version. Each sentence earns its place.

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 output schema and annotations carry some burden, but this is a 22-parameter tool with low schema coverage. The description covers the basic create flow but leaves out important contextual choices such as structured fields versus raw_vcard and how this differs from updating an existing contact. It is adequate for a simple call but not complete for sophisticated use.

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?

With only 27% schema description coverage across 22 parameters, the description needed to compensate, but it only clarifies that UID/file name are server-generated and mentions vCard version behavior. It does not explain how the many structured fields map to vCard, when to use raw_vcard, or how the address book parameter should be sourced.

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 and resource: 'Adds a card to an address book.' It also adds distinguishing detail by noting that the UID and file name are generated here, which separates creation from updating an existing contact.

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 gives no guidance on when to use this tool versus alternatives like update_contact, delete_contact, or import/export tools. It implies creation but does not state exclusions or direct the agent to a sibling for existing contacts.

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