Create n8n Credential

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

Annotations already signal a non-read-only, non-idempotent mutation. The description adds useful behavioral context by noting that the data object is 'specific to the credential type' and that projectId is optional. It also points to a necessary precursor step (getting the schema), which goes beyond the structured 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 compact: a two-sentence intro followed by a concise parameter list. While the parameter list partially duplicates schema descriptions, it is still structured and scannable. It doesn't waste words, and the prerequisite instruction 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?

For a credential-creation tool with 4 parameters and nested data, the description covers the key aspects: purpose, prerequisite (get schema), parameter semantics, and optional project assignment. No output schema exists, but the return value is not critical here. It could mention permissions or error cases, but the guidance is sufficient for an agent to invoke it correctly.

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 coverage is 100% with parameter descriptions for all four fields. The description's Args section mirrors the schema but adds minimal extra meaning: the note that data is 'specific to the credential type' and the '(string?)' marker for optionality. These are modest additions, so the baseline 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 begins with 'Create a new credential' — a specific verb and resource — and clearly distinguishes this from sibling tools like n8n_update_credential and n8n_delete_credential. It also references n8n_get_credential_schema as a prerequisite, which reinforces the tool's purpose.

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 instructs the agent to use n8n_get_credential_schema first to determine required fields, which is strong contextual guidance. It doesn't explicitly state when not to use this tool, but the prerequisite and the clear 'create' action imply when to use it relative to update/delete/test siblings.

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