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

Goes well beyond the annotations (which already state readOnlyHint=false, idempotentHint=true, destructiveHint=false) by naming the response keys the agent will see: "already" with an unchanged count, and "ambiguous" with "say_now". It also discloses the coverage boundary ("Only companies Whimbrel covers can be added") and that adding never starts a watch, which is exactly the kind of side-effect context annotations cannot convey.

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?

Front-loaded with the trigger condition and then sequenced in call order: what it does, what it does not do, what happens on duplicates, what happens on ambiguity. The quoted example utterances are useful but add some bulk; overall it stays tight with no filler sentences.

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 output schema, the description carries the return-value burden and does so for the two edge outcomes (already, ambiguous) plus the coverage restriction. The happy-path success shape (what a successful add returns) is not described, a minor gap for a tool with only two parameters.

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 both parameters are already documented; the description nonetheless adds real meaning by explaining that `website` is a retry input used after an ambiguous reply for a single company. It does not restate the 50-name cap or the name-format expectation, but the schema handles those.

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 plus resource: adds companies to the rep's own target set, and it explicitly frames that set as the same one the Whimbrel app shows. It is clearly distinguishable from siblings like remove_target, list_targets and watch_company, and it even states that adding does not trigger a watch.

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?

Opens with an explicit trigger condition ("Use this when the rep asks to add one or more companies to their targets") backed by two concrete example utterances. It also routes to the alternative ("offer in one line to watch the company too (watch_company)") and defines the fallback path when a name is ambiguous.

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