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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds that it searches the Microsoft 365 address book by name, email, or company, but does not disclose other behaviors like result limits, pagination, or whether the search is case-insensitive. This is consistent with annotations and adds some context, but not rich detail.

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 a single, clear sentence with no wasted words. It front-loads the action and resource, making it immediately understandable.

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 tool is simple with one parameter, an output schema, and safety annotations. The description sufficiently conveys the core purpose and scope. It does not explain return values, but the output schema covers that, and the annotations handle safety. A slightly higher score would require explicit guidance on alternatives or behavioral details, but for its simplicity, it is nearly complete.

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 provides 100% coverage for the single parameter 'query', describing it as a search term for name, email, or company. The tool description essentially repeats this information, adding no new meaning beyond what the schema provides. Baseline of 3 applies.

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 verb (search), resource (contacts), and scope (Microsoft 365 address book), and specifies the search fields (name, email, or company). It is distinct from list_contacts and get_contact, though it does not explicitly differentiate itself from sibling tools like search_contacts or search_m365_directory.

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 no guidance on when to use this tool versus alternatives such as list_contacts or get_contact. It does not state prerequisites, exclusions, or when not to use it, relying solely on the implied purpose of searching contacts.

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