get_gap_histogram

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

There are no annotations, so the description carries the full burden. It discloses the GAP definition and return format, but it does not explicitly state that the tool is read-only, what happens if an activity lacks elevation data, or any error conditions. Given the read-only nature is implied by 'get', this is adequate but not deeply transparent—hence a 3.

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 front-loaded with the primary purpose, followed by a concise explanation of GAP, then structured Args and Returns sections. Every sentence serves a purpose, and the format is easily scannable with zero fluff.

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 simple one-parameter tool with an output schema, this description is quite complete: it provides the purpose, the underlying concept, the input, and the return type. However, it could have explicitly mentioned that the operation is non-destructive (no annotations to confirm) or noted any prerequisites like elevation data. Still, it's well-rounded for the tool's simplicity.

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 input schema already fully describes activity_id as 'Activity ID to analyze' with 100% coverage. The description adds only 'The unique ID of the activity,' which is a minor nuance. Since the schema carries the parameter semantics, the description adds minimal value beyond the baseline of 3.

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 starts with 'Get grade-adjusted pace (GAP) histogram for an activity,' a specific verb and resource that clearly differentiates from sibling histogram tools (e.g., get_pace_histogram, get_hr_histogram) by highlighting 'grade-adjusted' and 'GAP'. It also explains the normalization concept, leaving no ambiguity about what the tool does.

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 explicitly states when to use it: 'Useful for trail running to understand true effort distribution independent of terrain.' This provides clear context, but it does not mention alternatives or when not to use it (e.g., flat terrain might use get_pace_histogram). While not as explicit as naming siblings, the guidance is actionable, so a 4 is appropriate.

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