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

The annotations already declare the key safety profile: not read-only, non-idempotent, non-destructive, open-world. The description adds meaningful context beyond that, including that credentials are stored as a password and that the operation requires a Pro or Agency plan. It does not say what happens on duplicate connection or whether the connection is validated before success.

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?

Three sentences, front-loaded with the core action, then the exclusion, then the plan requirement. Every sentence adds decision-relevant information and there is no repetition of schema details.

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 connection/mutation tool with no output schema, the description covers the key decision context: authentication type, the sibling alternative, 2FA implications, and plan gating. It leaves minor operational details unstated, such as duplicate handling and whether a connection test occurs, but the essential call guidance is present.

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%, with the nested `imap` object fully documented, including example hostnames and typical ports. The description adds no parameter-level detail beyond reinforcing 'username and password', so baseline 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 states a specific verb and resource: connecting a mailbox over IMAP/SMTP with a username and password. It also explicitly distinguishes this tool from the sibling `email_account_oauth_url`, so an agent can route Google/Microsoft mailboxes without opening either schema.

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?

It gives explicit when-not-to-use guidance: Google and Microsoft mailboxes should go through `email_account_oauth_url` instead, with the rationale that OAuth avoids storing a password and survives 2FA. It also states a prerequisite: 'Requires a Pro or Agency plan.'

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