Find contacts

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

Even with readOnlyHint, idempotentHint, and destructiveHint already set, the description adds valuable behavioral disclosure: it reveals one request is made per address book, fields are combined with OR in CardDAV, and results are re-checked because some servers only partially filter. This is exactly the kind of non-obvious runtime behavior an agent needs to anticipate.

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 sentences with no wasted words. The primary purpose is front-loaded, and the second sentence delivers the most important behavioral caveat. The parenthetical CalDAV contrast is brief and earns its place by highlighting a protocol-specific difference.

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 full input schema, a present output schema, and annotations covering safety and idempotency, the description supplies the remaining non-obvious context: partial server filtering and per-address-book request behavior. An agent has enough information to select and invoke the tool correctly.

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?

The schema already documents all four parameters with 100% coverage, so the baseline is 3. The description adds meaningful parameter behavior beyond the schema by explaining that fields are combined with OR and that requests are issued per address book, which clarifies how the fields and address_books parameters actually behave.

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 action ('Finds contacts') and precisely scopes the resource by listing the searchable fields: name, organisation, email address, phone number and note. This clearly differentiates it from sibling tools like list_contacts or get_contact, which do not perform term-based search across multiple fields.

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 intended use is implied by the search semantics, but the description never explicitly says 'use this when you need term search' or contrasts it with list_contacts/export_contacts for retrieving all contacts. The CardDAV versus CalDAV note provides protocol context but not actionable when-to-use versus when-not-to-use guidance.

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