list_allowed_recipients

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

Beyond the readOnly/idempotent/non-destructive annotations, the description discloses important behavior: case-insensitive matching, glob pattern support, the special meaning of '*', the empty-list denial effect, and that configuration happens through a user-operated CLI/UI. This gives the agent a strong model of the tool's semantics.

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 dense but tightly structured: the core action is front-loaded, then behavior and edge cases are added in a logical order. Every clause adds useful information and there is no 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?

With no parameters, a present output schema, and annotations covering the safety profile, the description covers all essential context: what is listed, how matching works, wildcard semantics, and the impact of an empty list. Nothing critical is missing for an agent to use this tool 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?

The tool has zero parameters and the schema already covers 100% of parameter documentation, so the description does not need to add parameter meaning. The baseline for zero-parameter tools is 4, and nothing here reduces that.

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 opens with a specific verb and resource: 'List the configured recipient allowlist'. It clearly distinguishes this from the sibling list_allowed_senders by defining the scope as recipient address patterns and naming the operations (send_email, forward_email, save_to_mailbox) that the allowlist constrains.

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 when this tool matters by explaining that the allowlist governs send/forward/save operations and that an empty list denies all recipients. It does not explicitly contrast with list_allowed_senders or state 'use this when you need recipient restrictions, not sender restrictions,' which would make the guidance fully explicit.

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