compare_workouts

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

Goes well beyond the readOnlyHint/openWorldHint annotations: discloses the API-call cost ('one API call per activity plus 1-3'), how intervals are classified (main set, surges, other, excluded), the comparison inclusion rule (length ±25%, intensity ±8 points of FTP), the reliability caveat (n < 3 not reliable), that RPE is whole-activity only, that gear/power meter differences are flagged, and that no verdict is issued.

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 purpose is front-loaded in the first clause, followed by dense but relevant operational detail. It is long and packed with parentheticals, which slightly taxes readability, but nearly every sentence carries information an agent needs to invoke and interpret the tool.

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 19-parameter, no-output-schema tool, the description covers selection scope, filtering defaults, interval classification, computed metrics (power, NP, HR, max HR, cadence, W/bpm), trend semantics, reliability thresholds, and known limitations. An agent has enough to call it correctly and interpret results without a return schema.

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 coverage is 100%, so the baseline is 3, but the description adds cross-parameter meaning: how the reference pattern is chosen (reference_activity_id, else the newest), that query and activity_ids are alternatives, and how interval filters replace defaults (e.g. min_intensity replacing the 70% floor). This adds genuine semantics beyond per-field schema text.

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?

States a specific verb and resource (compare repeated executions of the same workout over time) with the scope qualifier 'on truly comparable work intervals.' This clearly differentiates it from siblings like compare_best_efforts, find_similar_intervals, and compare_power_streams, which handle different comparison units.

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?

Gives a concrete usage trigger ('repeated executions of the same workout over time, e.g. every 3 x 10 min threshold session') and points to the method guide via get_guide. It does not explicitly name which sibling to use instead when the user wants a different kind of comparison, so routing is implied rather than spelled out.

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