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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety bar is low. The description still adds real value beyond them: no auth required, free, zero arguments, and a fixed enumeration of topics. It doesn't explain result shape, but an output schema covers that.

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?

Three short sentences, each carrying distinct information: what is returned, access/cost, argument count, and the fixed topic set. The core purpose is front-loaded with no redundancy.

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 annotations covering safety, an output schema covering return structure, and zero params, the description covers nearly everything an agent needs. The one missing link is that these topic names are presumably what create_alert consumes — an explicit tie to that sibling would close the gap.

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?

Zero parameters, so baseline is 4. The description explicitly states "Takes no parameters," confirming the empty schema rather than contradicting it.

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 webhook topics) plus what each entry contains (the source URL it watches), and enumerates the exact topic values. An agent can tell this apart from create_alert, which is the mutation counterpart, 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?

"Free, no auth" and "takes no parameters" give useful precondition context, and listing the topic names implies this is the discovery step before create_alert. But it never says explicitly when to call this versus create_alert, nor that these names may feed a subscription call — usage must be inferred.

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