n8n MCP Server

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

Annotations provide key behavioral hints (readOnlyHint=false, destructiveHint=false, idempotentHint=true), so the description doesn't need to repeat safety or idempotency. However, it adds minimal context beyond annotations—only stating it returns 'stopped execution details.' It could elaborate on effects (e.g., halts processing, may leave partial results) or constraints (e.g., permissions needed), but doesn't contradict annotations.

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 front-loaded with the core purpose ('Stop a running execution'), followed by brief parameter and return notes. It's efficient with no wasted sentences, though the Args/Returns formatting is slightly verbose for a single parameter. Overall, it's well-structured and to the point.

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?

Given the tool's moderate complexity (a mutation to stop executions), annotations cover safety and idempotency, but there's no output schema. The description mentions return details but lacks specifics (e.g., status fields, error handling). It's adequate for basic use but leaves gaps in understanding outcomes, especially without output schema support.

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%, with the parameter 'id' fully documented in the schema. The description adds no additional meaning beyond the schema's 'unique identifier of the resource,' merely restating it as 'Execution ID to stop.' This meets the baseline for high schema coverage but doesn't enhance understanding.

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 clearly states the specific action ('Stop a running execution') and identifies the resource ('execution'), distinguishing it from sibling tools like n8n_delete_execution (which removes) or n8n_retry_execution (which restarts). The verb 'Stop' is precise and 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?

No guidance is provided on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., the execution must be running), exclusions (e.g., cannot stop completed executions), or comparisons to siblings like n8n_delete_execution. The agent must infer usage from context alone.

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