list-supported-languages

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 that it returns localeInfo objects with specific fields and that it is sourced from the mailbox server, which is useful. It does not contradict any annotations, but it also does not disclose any additional behavioral traits beyond what annotations and schema already imply. With annotations covering the core behavior, the description provides modest added transparency.

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 plus a tip. The first sentence states the core purpose, and the second adds context about the flow. The tip is front-loaded with a bullet and provides concrete return format and usage advice. It is efficient without being overly terse, though the phrase 'You can subsequently get the preferred language by getting the user's mailbox settings' could be trimmed. Overall, it 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?

Since there is no output schema, the description properly explains the return format (localeInfo objects with locale and displayName). It also gives a practical validation use case. All parameters are documented in the schema, and the description covers the essential context. It does not mention pagination behavior, but the schema already covers $top/$skip/fetchAllPages, so nothing critical is missing.

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%, and each parameter (top, skip, count, filter, search, fetchAllPages, includeHeaders, excludeResponse) already has a detailed description in the input schema. The tool description does not add any parameter-specific guidance beyond what the schema provides. Per the calibration baseline for high schema coverage, a score of 3 is appropriate.

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 tool gets the list of locales and languages supported on the user's mailbox server. It specifies the exact resource and purpose, and distinguishes itself from the sibling list-supported-time-zones by focusing on languages/locales rather than time zones. The mention of 'localeInfo objects with locale (e.g. 'en-US') and displayName' further clarifies the output, making it unambiguous.

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 clear context: this list is used when setting up an Outlook client, and to validate a locale before calling update-mailbox-settings. It references get-mailbox-settings for retrieving the preferred language, effectively routing the agent to related tools. However, it does not explicitly state when not to use this tool or compare it to alternatives like list-supported-time-zones, so it lacks explicit exclusions—hence a 4 rather than a 5.

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