Recipient choices

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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds the real value of a capability gate and a named error outcome (UNSUPPORTED_CAPABILITY) for modern accounts. It stops short of describing hierarchy depth, ordering, or what an empty result means, but with an output schema present that omission is minor.

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?

Two sentences, zero filler, with the legacy-only precondition front-loaded before the follow-on guidance. Every clause carries actionable information.

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 2-parameter read tool with full schema description coverage, existing annotations, and an output schema, the description supplies the preconditions, the failure mode, and the next-step routing. An agent has everything needed to decide and call 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 coverage is 100%, so the baseline is 3; the description earns above baseline by explaining the data flow — the output's reference.selection_id becomes the recipient_type input for get_recipients, tying parameters to a concrete workflow. It does not explain the selection_id default of '0' or include_virtual, which the schema carries alone.

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 ('list') and resource ('sub-choices of a hierarchical recipient group, such as classes'), plus an explicit scope restriction ('Legacy accounts only'). It is clearly distinguishable from the siblings get_recipient_types (top-level groups) and get_recipients (final recipient list).

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 names the condition that selects this tool (legacy accounts with a hierarchical group), the condition that excludes it ('Modern accounts return UNSUPPORTED_CAPABILITY'), and the downstream step ('Put the chosen item's reference.selection_id into recipient_type for get_recipients'), routing the agent to the correct sibling.

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