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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds little beyond the basic read operation; it does not mention default limits, pagination, sorting, or outcome details, but with annotations providing the key behavioral cues this is acceptable.

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, concise, front-loaded sentence that communicates the core purpose without any wasted words. It is appropriately sized for a straightforward list operation.

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 simple nature of the tool, one optional parameter, and presence of an output schema and safety annotations, the description is mostly complete. The only notable omission is guidance about prerequisites (e.g., needing a connected M365 account) or when to use search instead of list, but this is not critical for a basic list operation.

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 input schema covers 100% of the single optional 'limit' parameter with a clear description, so the baseline is 3. The description adds no additional parameter context beyond the schema, but none is needed given the simple optional limit.

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 'List contacts from your Microsoft 365 / Outlook address book' uses a specific verb ('List') and clearly identifies the resource (contacts in M365/Outlook). It distinguishes itself from generic siblings like 'list_contacts' by explicitly scoping to the Microsoft 365 / Outlook address book.

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?

No guidance is provided about when to use this tool versus the many similar sibling tools such as 'm365_search_contacts', 'search_contacts', or 'get_contact'. There are no explicit alternatives or exclusions, leaving the agent to infer usage purely from the name and description.

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