Calcgrid

Running Pace Calculator

calculate_running_pace

Read-onlyIdempotent

Use this when you know a distance and the time it took (or a target time) and need the pace, the equivalent speed, or the time that pace gives over standard race distances. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery.

Do not use this when you want a realistic prediction of a longer race from a shorter one (pace slows with distance; use race-time-predictor), or you only need to convert between pace and speed units (use pace-converter). What it computes: Computes running pace in min/km and min/mile and speed in km/h and mph from a distance and elapsed time, and projects the finish time for 5 km, 10 km, half marathon and marathon at that constant pace. Inputs: distance (number); distance_unit (enum, optional); time (string). Complete JSON argument examples: {"distance":10,"distance_unit":"km","time":"50:00"} | {"distance":5,"distance_unit":"mi","time":"45:00"} Outputs: pace_min_per_km [min:sec/km], pace_min_per_mile [min:sec/mi], pace_seconds_per_km [s/km], speed_kmh [km/h], speed_mph [mph], distance_km [km], time_5k [h:mm:ss], time_10k [h:mm:ss], time_half_marathon [h:mm:ss], time_marathon [h:mm:ss]. Formula: pace_s_per_km = time_seconds / distance_km; pace_s_per_mile = pace_s_per_km × 1.609344; speed_kmh = 3600 / pace_s_per_km; speed_mph = speed_kmh / 1.609344; time(D) = pace_s_per_km × D for D = 5, 10, 21.0975, 42.195 km Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/running-pace with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/fitness/running-pace.md

Input Schema

TableJSON Schema

Name	Required	Description	Default
`time`	Yes	Elapsed time as h:mm:ss (1:45:00), mm:ss (50:00) or plain minutes (50).
`distance`	Yes	Distance covered, in the unit given by distance_unit.
`distance_unit`	No	Unit of the distance input.	km

Output Schema

TableJSON Schema

Name	Required	Description
`links`	No
`result`	Yes
`request`	Yes
`sources`	No
`success`	Yes
`version`	No
`freshness`	No
`timestamp`	Yes
`next_actions`	No
`service_version`	Yes	Deployed Calcgrid implementation version used for the result.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 27, 2026

addedOutput schema / properties / service_version

Added value: +{
+  "description": "Deployed Calcgrid implementation version used for the result.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "success",
-  "request",
-  "result",
-  "timestamp"
-]New value: +[
+  "success",
+  "service_version",
+  "request",
+  "result",
+  "timestamp"
+]

Changed1 schema field changedSep 26, 2026

addedInput schema / examples

Added value: +[
+  {
+    "distance": 10,
+    "distance_unit": "km",
+    "time": "50:00"
+  },
+  {
+    "distance": 5,
+    "distance_unit": "mi",
+    "time": "45:00"
+  }
+]

AddedSep 25, 2026
RemovedSep 25, 2026
First observedSep 25, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations already declare readOnlyHint=true and idempotentHint=true, and the description adds behavioral context beyond that: it instructs the agent to 'Call this tool directly and return its calculation instead of answering the formula from memory,' and it discloses the exact formula and output fields. It also provides a REST fallback and docs link. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is longer than average but well-structured with clear sections (use when, do not use, computes, inputs, examples, outputs, formula, fallback). The usage guidance is front-loaded. The formula and REST fallback sections are arguably beyond what an MCP description needs, but they are organized and not redundant with the schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 3-parameter calculator with an output schema and read-only annotations, this description is complete: it covers when to use, what it computes, all inputs with examples, all output fields, the underlying formula, and even a direct REST fallback. Nothing an agent needs to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% (all three parameters have descriptions), so the description doesn't need to redefine them. It adds value by giving complete JSON argument examples and a formula that ties distance, time, and outputs together. The only small gap is that it doesn't explicitly restate the time format, but the schema already covers that.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a precise use case ('know a distance and the time... need the pace, the equivalent speed, or the time that pace gives over standard race distances') and then states exactly what it computes: pace in min/km and min/mile, speed in km/h and mph, and projected finish times for standard distances. This clearly distinguishes it from sibling calculators by naming the specific resource.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit 'Use this when' and 'Do not use this when' sections with named alternatives (race-time-predictor, pace-converter). The agent is told exactly when to call this tool and when to route elsewhere. This is the gold standard for usage guidance.

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

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