MCP Email Service

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds useful context about the tool running 'against the live mailbox' and the recommendation for account_id, which hints at real-time effects and potential multi-account issues. However, it lacks details on permissions, rate limits, or error handling, leaving gaps for a mutation tool.

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 front-loaded with the core purpose in the first clause and follows with operational context in a second sentence. Every sentence earns its place by providing essential information without redundancy, making it efficient and well-structured.

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 as a mutation operation with no annotations and no output schema, the description is somewhat complete but has gaps. It covers the action and some behavioral context but lacks details on return values, error cases, or full usage scenarios, which could hinder agent effectiveness in edge cases.

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%, so the schema already documents all parameters thoroughly. The description does not add any additional meaning or clarification beyond what the schema provides, such as explaining flag_type semantics or folder implications. Baseline 3 is appropriate as the schema handles the heavy lifting.

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 specific action ('Flag/star or unflag an email') and resource ('an email'), distinguishing it from siblings like mark_email_read or delete_email by focusing on flagging operations. It uses precise verbs and identifies the target resource without ambiguity.

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 clear context for usage by noting it 'runs against the live mailbox' and recommends 'account_id to avoid cross-account lookups', which helps guide when to use it. However, it does not explicitly state when not to use it or name alternatives among siblings, such as batch operations or other email modifications.

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