people_search_contacts

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

Beyond the readOnlyHint and idempotentHint annotations, the description discloses the personal-address-book-only scope, the fact that it returns emails and phone numbers, and the required permission (Contacts.Read). This adds meaningful behavioral context that annotations alone do not provide.

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?

Three sentences with no wasted words: purpose is front-loaded, differentiation is immediately clear, and the permission requirement is stated at the end. Every 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?

Given the tool's simplicity (2 params, no output schema), the description fully covers what the tool does, what it returns, when to use it, and what permission is needed. It is complete for an agent to decide on 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?

Schema description coverage is 100%, so the baseline is 3. The description's 'name or company' phrasing mirrors the query parameter's schema description and adds no new semantic detail. max_results is already well-described in the schema, so no compensation needed.

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 uses a specific verb ('Search') and resource ('signed-in user's saved Outlook contacts') with clear scope ('by name or company') and output ('returning emails and phone numbers'). It also explicitly distinguishes itself from sibling tools by naming people_search and directory_search_users, making the tool's unique role clear.

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 when-to-use guidance: it states this searches only the personal address book and directs users to alternative tools for other scopes (colleagues via people_search, whole tenant via directory_search_users). It even highlights that this is the one for external contacts, giving clear selection criteria.

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