Recipient types

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the security profile is known. "Sends nothing" adds real reassurance that this discovery call cannot dispatch a message, a non-obvious property for a messaging tool. It does not mention pagination or behavior for accounts with zero messageable groups, keeping it short of 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?

Three short sentences: what it returns, how to use the result, and a safety note. The core purpose is front-loaded and every sentence earns its place.

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?

An output schema exists, so return values need not be explained, and the usage routing to sibling tools is fully covered. Only edge-case behavior (invalid alias, empty group list) is left implicit, which is minor for a one-parameter read tool.

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% and the single account_alias parameter is fully documented with format constraints and a pointer to list_accounts. The description adds no parameter-level detail beyond the schema, so 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?

Specific verb and resource: "List the recipient groups this login can message and whether each can be looked up." It also scopes to the current login, which distinguishes it from get_recipients/get_recipient_choices that operate on the groups themselves.

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?

Explicitly routes the agent: pass a group's reference to get_recipients, and on legacy accounts to get_recipient_choices. Both alternatives and the condition that selects between them are stated, leaving nothing to inference.

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