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

Annotations only declare readOnlyHint and openWorldHint; the description goes well beyond them by disclosing pagination (20 per page), the exact semantics of healthScore (0-100, share of warm-up emails landing in inbox over the last 7 full days), how it moves daily, and the null conditions (warm-up off or fewer than 20 emails checked). This is rich behavioral context an agent could not infer from structured fields.

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?

Front-loaded with the core purpose and filters before the longer healthScore explanation, and each sentence carries information. The healthScore block is lengthy but justified given there is no output schema.

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?

With no output schema, the description usefully explains the key derived return field (healthScore) and its nullability, plus page size defaults. Other returned fields (daily limits, connection status) are named but not elaborated, leaving a small gap.

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 five parameters are already documented in the schema, and the description largely restates the same filter intents (campaign, connected/disconnected, workspace). It adds only marginal value, so the 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?

States a specific verb+resource ('Lists the sending email accounts in the workspace') and immediately enumerates the returned fields (connection status, daily limits, health score). An agent can clearly separate this bulk-listing tool from the singular get_sender_email sibling.

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 filtering scenarios ('Filter to one campaign's senders, to connected or disconnected mailboxes only, or to one workspace on the account') and a concrete selection rationale ('Use it to pick the accounts to add to a campaign'). It lacks an explicit when-not-to-use or a named alternative such as get_sender_email for a single account.

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