mailkite_list_route_candidates

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

Beyond the readOnlyHint annotation, it discloses ordering ('newest first'), row semantics (delivered_here), a detailed pagination contract (bounded scan, short pages, continue until nextBefore is null), and the required management session token. This is substantial behavioral context that annotations do not provide.

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?

Four sentences, each carrying a distinct piece of information: what the tool returns, how to use delivered_here, how pagination behaves, and what auth is required. The purpose is front-loaded 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?

The description covers purpose, ordering, auth, and a pagination loop, but it references `before` and `limit` parameters that are absent from the input schema, so an agent cannot act on the pagination instructions through the declared interface. With no output schema, the row shape is also only partially specified.

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?

With 100% schema coverage the baseline is 3, and the description at least suggests that `id` refers to 'this route'. However, it instructs the agent to page with `before` even though the input schema only accepts `id` and sets additionalProperties to false, so the parameter guidance is partly unimplementable and `id` is never explicitly defined.

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 identifies the resource ('stored inbound messages this route could be asked to deliver') and the purpose ('preview for replaying mail to a route defined after that mail arrived'). It does not state an explicit imperative verb like 'list' or name a sibling tool for contrast, so it is one notch below the clearest possible definition.

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 gives actionable context: use this preview before replaying mail, and use the delivered_here flag to send only messages the route has not seen. It does not explicitly enumerate alternatives or state when not to use it, but the context is clear enough to route an agent.

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