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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, openWorldHint=false), so the bar is lower. The description still adds real context: secrets are deliberately excluded from the response, the required credential format ('Authorization: Bearer <key>') and the fact that trial-tier keys fail with 403. Missing only secondary traits such as rate limits 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?

The core sentence is front-loaded and dense with useful facts, and the auth constraint follows immediately. The trailing 'Informational market data only; not investment advice' is legal boilerplate that does not help an agent select or invoke the tool, costing it a point.

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?

Even without an output schema, the description explains what comes back (hooks, plan, hook limit, secrets redacted) and which credentials are required or rejected. For a parameterless read tool this covers everything an agent needs before calling it.

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?

The tool takes zero parameters and the input schema is a closed empty object at 100% coverage, so the baseline is 4. There is nothing further the description could add about arguments.

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 ('List the webhook alert hooks registered for your API key') and names exactly what is returned (hooks, plan, hook limit) with a scope qualifier ('no secrets'). It is clearly distinguishable from register_alert_webhook, delete_alert_webhook and test_alert_webhook 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?

Usage is implied by the name and by the auth requirement ('Needs an API Light, Pro or internal key... trial keys get 403'), which tells the agent whether it can call it at all. However, it never says when to prefer this over get_latest_brief, get_history or the register/delete/test siblings, so the routing guidance is left to inference.

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