read_mail

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context beyond those annotations by specifying the return scope ('bounded plain text and recipients') and explicitly stating negative behaviors ('Does not download attachments or change read status'). This gives an agent concrete expectations for side effects and output content.

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 efficient sentence that front-loads the core action, then covers the most important return contents and non-effects. Every clause earns its place, with no redundant or filler language.

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?

For a one-parameter read operation with no output schema, the description provides enough behavioral and output context: it names what is included, what is excluded, and confirms no state change. It could additionally mention how to obtain a valid messageId, but the schema already states the ID comes from a mail tool, and sibling discovery tools are evident.

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 coverage is 100%, and the schema already describes messageId as 'Exact message or folder ID returned by a mail tool.' The description does not add any new meaning to the parameter beyond reinforcing that it identifies an exact message. Baseline 3 is appropriate because the schema carries the parameter documentation burden.

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 verb ('Read') and resource ('an exact message from your own Outlook mailbox'), and adds precise scoping details: bounded plain text and recipients. It also explicitly differentiates from sibling tools by noting it does not download attachments or change read status, distinguishing it from listing, searching, or draft-creation tools.

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 usage context is implied rather than explicit: 'Read an exact message' suggests the caller already has a messageId, and sibling tools like list_mail_messages and search_mail are the likely discovery tools. However, the description never states 'use this when you have a messageId' or explicitly contrasts with list/search alternatives, so guidance is implied rather than stated.

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