Intervals.icu MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It describes a read operation ('Get a list'), which implies it's non-destructive, but doesn't cover other critical aspects like authentication needs (though API key is a parameter), rate limits, error handling, or what the output contains. For a tool with no annotations and multiple parameters, this leaves significant gaps in understanding its 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 well-structured and appropriately sized. It starts with a clear purpose statement, followed by a bullet-point list of parameters with concise explanations. Every sentence adds value, and there's no redundant information. However, it could be slightly more front-loaded by integrating key parameter details into the initial sentence, but it's still highly efficient.

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 complexity (6 parameters, no annotations, but has an output schema), the description is mostly complete. It thoroughly documents all parameters, which is crucial since schema coverage is 0%. The presence of an output schema means return values don't need explanation in the description. However, it lacks behavioral context (e.g., auth, limits) and usage guidelines, which are minor gaps in an otherwise solid description.

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 description adds substantial meaning beyond the input schema, which has 0% schema description coverage. It explains all six parameters: their purposes (e.g., 'athlete_id: The Intervals.icu athlete ID'), optionality, defaults (e.g., 'defaults to 30 days ago'), and formats (e.g., 'YYYY-MM-DD format'). This fully compensates for the lack of schema descriptions, providing clear and complete parameter semantics.

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: 'Get a list of activities for an athlete from Intervals.icu'. This specifies the verb ('Get'), resource ('activities'), and source ('Intervals.icu'), making it easy to understand what the tool does. However, it doesn't explicitly differentiate this tool from sibling tools like 'get_activity_details' or 'get_events', which also retrieve activity-related data, so it doesn't reach the highest score.

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 provides no guidance on when to use this tool versus alternatives. It doesn't mention sibling tools like 'get_activity_details' (for specific activity data) or 'get_events' (for events vs. activities), nor does it specify prerequisites or contexts for use. The only implied usage is for retrieving activity lists, but this is basic and lacks explicit alternatives or exclusions.

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