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

Annotations already indicate non-read-only, destructive, idempotent behavior. The description adds useful behavioral specifics: the operation is a full replacement, endpoint/watched resource are immutable, and any llmContext guidance in results should be followed. This complements the annotations without contradicting them.

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 description is two sentences with no filler. It front-loads the core operation, then states the key constraint and an actionable alternative. Every sentence earns its place.

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?

Combined with a fully documented 4-parameter schema, an output schema, and sibling context, the description gives enough information to select and invoke the tool correctly. The only minor gap is the unexplained phrase 'webhooks group,' which creates a small amount of ambiguity.

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%, and each parameter already has a meaningful description—for example, enabledEvents is described as 'Full replacement of the subscription's event list.' The tool description adds no new parameter-level detail, so the baseline score of 3 is appropriate.

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?

The description opens with a specific verb and resource: 'Replace a webhook subscription's event list,' which directly states what the tool does. It also distinguishes itself from siblings by noting that the endpoint and watched resource cannot change, so the agent knows this is not a general 'update subscription' tool.

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?

The description explicitly states when to use the tool (to replace the event list) and when not to use it: 'The endpoint and watched resource cannot change — delete and recreate the subscription for that.' This names a clear alternative and condition, which is strong usage guidance.

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