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

Adds substantial behavior beyond the provided annotations: the global control-plane key is always restricted to account IDs owned by the authenticated user, future matching accounts are added by default, explicit account_ids without a providers filter stay restricted even with auto_include_new_accounts=true, and the signing secret is encrypted server-side and never returned by MCP. These are non-obvious operational and security constraints that materially affect safe invocation.

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?

Front-loaded with the core purpose, followed by dense but useful behavioral, security, and workflow guidance. Every sentence carries operational meaning, though the paragraph could be broken into shorter units for readability.

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?

For a 7-parameter mutation tool with no output schema, the description covers the most important behavioral and security context, plus a workflow recommendation. It does not enumerate runtime options or explain event selection, but those are largely handled by the schema's event descriptions and the sibling webhook_list_available_events tool.

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 57%, so the description must compensate. It clarifies the important interaction between account_ids, providers, and auto_include_new_accounts, and implies the request_url workflow via the n8n Test/Production URL guidance. It does not explain the name or runtime parameters, leaving some gaps.

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 ('Create a realtime event destination') that clearly distinguishes it from sibling webhook_update_destination, webhook_delete_destination, and webhook_list_destinations. It lacks explicit sibling naming, but the create operation is unambiguous.

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?

Provides clear procedural guidance for n8n users (Test URL, validate with a Development/Mock event, then update to Production URL) and a security warning not to ask for the signing secret. It does not explicitly state when to use this tool versus webhook_update_destination or when creation is inappropriate, so it stops 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.