create_webhookCreate an SSRF-checked webhook subscription for app install, event, decision, or fraud notifications; returns the signing secret once for verification.
Create an SSRF-checked webhook subscription. Returns the signing secret once.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | ||
| app_id | No | ||
| description | No | ||
| event_types | Yes | ||
| idempotency_key | No | Stable retry key for this exact mutation. |
Changes observed during successful MCP inspections.
v2.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the mutation profile (readOnly=false, destructive=false, idempotent=false, openWorld=true). The description adds two genuinely useful facts not in the annotations: the URL is SSRF-validated (internal addresses will be rejected) and the signing secret is returned only once and cannot be re-fetched. It stops short of explaining idempotency_key behavior or failure modes.
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?
Two sentences, front-loaded with the action and the highest-risk behavior (one-time secret). Nothing wasted.
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?
It covers the two highest-stakes facts (SSRF validation, one-time secret), but with 5 params at 20% coverage and no output schema, an agent still lacks guidance on app_id scoping, event_types selection, and what the response contains besides the secret.
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 only 20% — just idempotency_key is documented. The description does not explain url, app_id, description, or event_types, and only obliquely signals that url is validated. With 5 params and low coverage, the description should compensate and does not.
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+resource ("Create ... webhook subscription") and adds a qualifier (SSRF-checked). It is obviously distinct from list_webhooks/delete_webhook, though it never names them explicitly.
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?
There is no statement of when to use this versus list_webhooks/delete_webhook, nor any prerequisite (e.g. required scopes, whether an app must exist first). Only the implicit "create" semantics convey usage.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.