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

Annotations only declare openWorldHint and destructiveHint=false, and the description adds substantial context: the app-password requirement, provider exclusions, domain rejection behavior, and that the returned account's healthScore stays null until warm-up scans 20 emails. It stops short of covering auth prerequisites for the API or failure/error modes, so a 4 rather than a 5.

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?

Four front-loaded sentences that each carry a distinct constraint (mechanism, provider exclusion, domain rule, return semantics). No filler, though it is denser than strictly necessary for a short description.

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 7-parameter creation tool with no output schema, the description covers the key behavioral surprises: eligibility rules, the non-automatable providers, and the null healthScore return value. An agent has everything needed to call it correctly.

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 all seven parameters including app-password and business-domain semantics are already documented in the schema. The description reinforces the business-domain constraint but adds no syntax or format detail beyond what the schema provides, so the baseline 3 applies.

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?

States a specific verb (connects) and resource (SMTP/IMAP mailbox to workspace) with the mechanism (app password, no browser). It explicitly distinguishes itself from siblings by naming get_sender_email and contrasting with the in-app flow for Google/Microsoft.

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?

Gives explicit when-not-to-use (Google and Microsoft mailboxes require interactive consent and must be connected in the app) and a hard eligibility rule (business domain only, gmail.com rejected). The agent can route correctly without further inference.

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