Intervals.icu MCP Server

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

With no annotations provided, the description carries full burden for behavioral disclosure. It describes what data is returned but doesn't mention authentication requirements beyond the optional api_key parameter, rate limits, pagination, error conditions, or whether this is a read-only operation. The description is functional but lacks important operational context.

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 with a clear purpose statement followed by detailed parameter documentation. It's appropriately sized for a tool with 3 parameters and comprehensive parameter documentation needs. The information is front-loaded with the core purpose first. Minor deduction for some redundancy in listing metrics both in the purpose statement and parameter details.

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 has an output schema (which handles return values), 3 parameters with 0% schema coverage, and no annotations, the description does well by thoroughly documenting all parameters. It covers what data is returned and parameter semantics. The main gap is lack of behavioral context like authentication, rate limits, or error handling, but the output schema reduces the need to describe return format.

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?

With 0% schema description coverage, the description fully compensates by providing detailed parameter documentation. It explains activity_id's purpose, clarifies api_key's optional nature and fallback behavior, documents stream_types' format and default values, and lists all available stream types. This adds significant value beyond the bare 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: 'Get stream data for a specific activity from Intervals.icu' with specific metrics listed. It distinguishes from siblings like get_activity_details or get_activities by focusing on time-series stream data rather than summary or interval data. However, it doesn't explicitly contrast with these siblings in the description text itself.

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 like get_activity_details or get_activity_intervals. It mentions the tool's scope but doesn't indicate scenarios where stream data is needed over other activity data types, nor does it mention prerequisites or exclusions.

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