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

Annotations already flag readOnlyHint=false, openWorldHint=true, destructiveHint=false. The description adds genuinely useful behavior beyond that: API key requirement, free-account prerequisite, and that frequency is clamped to the plan. It stops short of describing what happens on creation (e.g., returned watch identifier).

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 fragments that each carry information, no filler. The telegraphic style ('Monitor. Watch...') is terse but readable and efficient.

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 4-parameter mutation with no output schema, the description covers inputs and prerequisites well, but says nothing about the result of creating a watch (ID, confirmation, error behavior). Adequate but with a clear gap for a creation tool.

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 75%, and the description compensates by naming the enum values (weekly/daily/12h/4h), specifying the https-only constraint on webhook_url, and clarifying that signals is optional. 'Clamped to the plan' adds a constraint absent from the schema.

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 and resource ('Watch a company site and get alerts when public signals change') and clearly positions itself against siblings like cancel_monitor_watch and list_monitor_watches. An agent can identify it without opening the 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?

Gives prerequisites ('Requires an API key', 'Needs a free StartupHub.ai account') which imply when it can be called, but never states when to use it versus alternatives such as list_monitor_watches or conditions for creating a watch. Usage is implied rather than explicit.

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