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

Annotations only establish readOnly=false, destructive=false, openWorld=false; the description adds genuinely new behavior: the update is partial (at least one field), the signing secret is immutable and rotation requires delete+create, and the enabled flag pauses rather than queues events. It does not cover failure modes (invalid URL, unknown webhookId), so it is not 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?

Three compact sentences, front-loaded with the required-field rule, then the immutability caveat, then the return value. Every clause carries information; nothing is padding.

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 no output schema, the description sensibly states 'Returns the updated webhook,' and partial-update semantics plus secret immutability are covered. For a mutation tool with a nested headers object, it could say more about validation or error behavior, but nothing essential to invoking it correctly is missing.

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 all five parameters — including the required webhookId with its provenance ('from formWebhook_list or formWebhook_create') and the replace-not-merge semantics of headers — are already documented in the schema. The description merely lists field names and adds no syntax or constraint beyond what the schema states, matching the baseline 3.

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?

Names a specific verb and resource ('Update a form webhook') and immediately enumerates the mutable surface (url, headers, includeSchema, enabled), which cleanly separates it from formWebhook_create, formWebhook_delete, formWebhook_list, and formWebhook_test. An agent can identify the tool's role 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 a real usage constraint ('provide at least one field') and names the correct alternative workflow for a related task ('The signing secret never changes; delete and create again to rotate it'), routing to formWebhook_delete plus formWebhook_create. It lacks explicit when-not-to-use guidance (e.g. use create instead when the webhook does not yet exist), so it falls short of a 5.

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