Resolve a stats.fm user ID or custom handle to a user profile, searching when the identifier is not found.
Resolve a stats.fm user id or customId to their profile (falls back to user search)
| Name | Required | Description | Default |
|---|---|---|---|
| user_id | Yes | stats.fm user id or customId (e.g. "martijn") | |
| response_format | No | 'concise' = human prose, 'detailed' = more fields in prose, 'json' = raw API object | concise |
Changes observed during successful MCP inspections.
v1.29.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the burden of explaining behavior. It reveals a fallback behavior (user search) which is useful, but it does not explicitly state whether the operation is read-only, whether it makes network requests, or any other side effects. This leaves some ambiguity about the tool's runtime behavior.
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 a single, concise sentence that packs the core functionality and the fallback behavior. It is well-structured and to the point, with no superfluous words. This makes it easy for an agent to quickly grasp the tool's purpose.
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 simplicity of the tool (two parameters, no output schema), the description is adequate. It states what the tool does and the fallback behavior, which is sufficient context for an agent to determine when to call it. It does not need to elaborate on return values or other details since there is no output schema and the tool's scope is narrow.
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 schema covers both parameters with detailed descriptions: 'user_id' includes an example, and 'response_format' enumerates values with explanations. Since the schema coverage is 100% and the descriptions are thorough, the tool description itself does not add extra meaning beyond what is already in the parameter definitions. The baseline of 3 applies because the description does not supplement the schema.
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 tool's purpose: to resolve a stats.fm user ID or customId to their profile. It uses a specific verb ('Resolve') and names the resource (stats.fm user profile), making it unambiguous. The mention of the fallback to user search also provides additional context, distinguishing this from a simple ID lookup.
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 when to use the tool by noting that it falls back to user search, suggesting that it is appropriate when you have an ID and want the corresponding profile, and that search is a fallback if the ID is not found. However, it does not explicitly contrast with sibling tools like 'search' or 'get_user_profile', which would give clearer guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.