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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered without the description. The description adds that the result is a set of valid options for draft creation, which is useful behavioral context, but says nothing about permissions, scoping by project/site, or result ordering.

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?

A single well-formed sentence with the resource front-loaded and zero padding. It is efficient, though the brevity comes at the cost of the disambiguation noted elsewhere rather than being a structural flaw in itself.

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 simple read-only two-parameter lookup, the description conveys the return contents in natural language, which partly compensates for the absent output schema. It is still incomplete: the sibling overlap with list_outreach_templates and the meaning of the two required IDs are both unaddressed.

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 0% and neither required parameter (projectId, siteId) has any description or enum. The description does not mention either identifier, so the agent gets no help understanding whether the options are scoped to a site, a project, or both.

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 sender identities and templates a new draft can use' tells an agent exactly what is returned and what it is for. However, the sibling list_outreach_templates clearly overlaps with the templates half of this tool, and the description does nothing to distinguish the two.

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 phrase 'a new draft can use' implies a pre-draft lookup, but there is no explicit when-to-use statement, no prerequisites, and no mention of the sibling list_outreach_templates that an agent would plausibly pick instead. The routing decision is left entirely to inference.

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