Better Email MCP

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

Annotations provide key behavioral hints (readOnlyHint=false, destructiveHint=false, etc.), and the description adds useful context beyond this, such as how reply and forward actions handle subject lines and thread headers. However, it lacks details on potential side effects, error conditions, or rate limits, which would enhance transparency further.

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 highly concise and well-structured, using two sentences that efficiently cover the tool's actions and key behavioral details without redundancy. Every sentence adds value, making it easy to understand at a glance.

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 complexity (9 parameters, no output schema) and rich annotations, the description is mostly complete, covering core functionality and behavioral traits. However, it could be more comprehensive by including information on error handling or response formats, which would improve completeness for a tool with no output schema.

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?

With 100% schema description coverage, the input schema already documents all parameters thoroughly. The description adds minimal semantic value by mentioning 'reply maintains thread headers' and 'forward includes original body', but does not elaborate on parameter interactions or usage nuances beyond what the schema provides, aligning with the baseline for high coverage.

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's purpose with specific verbs ('send emails: new, reply, forward') and distinguishes it from sibling tools like 'attachments', 'folders', 'help', and 'messages' by focusing exclusively on email sending functionality. It provides concrete details about how reply and forward actions work, making the purpose 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 implicitly guides usage by explaining the differences between 'new', 'reply', and 'forward' actions, including how reply maintains thread headers and auto-prepends 'Re:', and forward includes original body and auto-prepends 'Fwd:'. However, it does not explicitly state when to use this tool versus alternatives or mention any exclusions, which prevents a perfect score.

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