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

Beyond the destructiveHint annotation, the description discloses that removal affects every inbox in the account, including other callers', that the call returns no body, and that read-only entries cannot be removed. These behavioral warnings and side effects are valuable context the annotations do not convey.

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, each earning its place: purpose and key scoping warning first, then the alternative tool, then a safeguard precondition. The strongest warning is front-loaded and there is no redundant filler.

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 destructive account-wide mutation operation, the description covers the core action, scope, side effects, prerequisites, and the relevant sibling. Without an output schema, it also discloses that no body is returned, so no critical calling context is missing.

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?

The schema already documents all four parameters with full coverage, so the baseline is 3, but the description adds meaning by tying `read_only` entries to a removal constraint and clarifying the account-wide nature of the list. This goes slightly beyond the schema field descriptions.

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: 'Removes one entry from an account-wide allow or block list.' It also explicitly differentiates this tool from the inbox-scoped sibling, making its scope unmistakable.

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 clearly names the alternative `delete_agentmail_inbox_list_entry` as the narrower action, giving an explicit when-not-to-use condition. It additionally instructs the agent to check `read_only` with `get_agentmail_list_entry` before attempting removal, providing a concrete prerequisite.

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