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 only mentions that the API key is optional with fallback to .env, but doesn't describe authentication requirements, rate limits, error handling, or what 'detailed information' includes. For a read operation with zero annotation coverage, this is insufficient behavioral 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 efficiently structured with a clear purpose statement followed by parameter explanations. The two-sentence format with bullet-like 'Args:' section is readable and front-loaded. No wasted words, though the parameter section could be more integrated with the main description.

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 2 parameters with 0% schema coverage, an output schema exists (which helps), but no annotations. The description covers basic parameter meaning and authentication fallback, but lacks behavioral context, sibling differentiation, and detailed usage guidance. For a simple read operation, this is minimally adequate but has clear gaps in completeness.

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 description coverage is 0%, so the schema provides no parameter documentation. The description adds basic semantics for both parameters: 'activity_id' as 'The Intervals.icu activity ID' and 'api_key' with optional/env fallback behavior. This compensates somewhat but doesn't provide format examples, constraints, or relationship between parameters. Given the coverage gap, this is minimal adequate compensation.

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 verb 'Get' and resource 'detailed information for a specific activity from Intervals.icu', making the purpose evident. However, it doesn't explicitly differentiate from siblings like 'get_activities' (list) vs 'get_activity_details' (single item), which would require a 5. The description is specific but lacks sibling distinction.

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_activities' or 'get_event_by_id'. It mentions optional API key handling but gives no context about use cases, prerequisites, or comparisons with sibling tools. This leaves the agent without clear direction on tool selection.

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