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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), and the description adds two useful facts not in them: an 'approved company' prerequisite and that user confirmation is required. The detailed two-step token flow is left to the schema, so it is not quite exhaustive.

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 tightly written sentences with the action and its purpose front-loaded; no filler or repetition.

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 two-parameter mutation tool with no output schema, the description plus the fully documented schema and annotations give an agent enough to call it correctly. The confirmation handshake is explained in the schema rather than the description, which is acceptable but leaves a small gap at the description level.

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%, so the schema already documents both parameters including the confirmation_token flow. The description only echoes the 'approved company' constraint on listing, adding little beyond the schema — 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?

States a specific verb (add), resource (company to the user's watchlist) and the benefit (notified when its record changes). An agent can immediately distinguish it from watchlist_remove or get_watchlist without opening any schema.

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?

Implies the usage context clearly (add to be notified of record changes) and flags the confirmation prerequisite, but never names alternatives such as watchlist_remove/get_watchlist or states when NOT to use it.

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