Verify that your Marvin API token is valid by testing it against the API. Returns OK when authentication succeeds, so you can confirm access before using other tools.
Check that the API token works against Marvin's API. Returns OK if the apiToken works.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations provide readOnlyHint=true, and the description adds meaningful behavioral context by specifying that a successful check returns OK if the API token works. This clarifies the tool's non-destructive auth-testing behavior beyond what annotations alone state.
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 only two short sentences, front-loading the core purpose ('Check that the API token works') and then specifying the success result. Every word contributes value, with no redundancy.
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 zero-parameter, read-only connectivity check with an output schema present, the description fully covers what an agent needs to invoke it correctly. The safety profile is captured by annotations, and return semantics are succinctly stated.
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?
The tool has zero parameters, so the baseline of 4 applies. The description mentions apiToken conceptually, but since there is no schema to document, no parameter-level detail is needed or missing.
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?
Description uses a specific verb ('Check') with a clear resource ('API token' against Marvin's API) and states the expected result ('Returns OK if the apiToken works'). This clearly distinguishes the tool from sibling tools like get_account_info or get_rate_limit_status.
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 implies the tool is for verifying API token validity but provides no explicit guidance on when to choose it over alternatives. No sibling exclusions or conditions are given, so an agent must infer usage from the tool name and description alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.