CVP verified calculation capability
Phrase modes: P% of X, what percent, of-what, percent change, adjust ±P%, and percentage difference.
Math Capability ID math.percentage version 1.2.0 CVP VERIFIED CURRENT Core
P% of X
Y = X × P / 100P = 100 × X / YY = 100 × X / PΔ% = 100 × (new − old) / |old|Y = X × (1 ± P/100)Δ% = 100 × |A − B| / ((A + B) / 2)Modes: of · is-what · of-what · change · adjust-up · adjust-down · difference
Canonical symbols for this capability. Agent schemas remain the contract.
| Symbol | Quantity | Unit | Role |
|---|---|---|---|
p | scalar ratio | — | input / output |
x | — | — | input / output |
y | — | — | input |
oldV | — | — | input / output |
newV | — | — | input / output |
a | — | — | input |
b | — | — | input |
dir | — | — | output |
value | — | — | output |
P | scalar ratio | — | output |
X | — | — | output |
Y | — | — | output |
delta | — | — | output |
percent_change | scalar ratio | — | output |
A | — | — | output |
B | — | — | output |
average | — | — | output |
percent_difference | scalar ratio | — | output |
unit | — | — | output |
Inspectable numeric contract for this Capability@Version. Not a rewrite of the engine.
| Field | Declaration |
|---|---|
numeric_domain | real |
exactness | float64 |
algorithm | Seven percentage formulas evaluated as exact rational expressions of normalized binary64 inputs, then one ties-to-even rounding per published field. |
valid_domain | Finite binary64 decimal operands (at most512 characters per token); active matching aliases; nonzero denominators. Difference requires A,B≥0 and nonzero sum. |
singularity_policy | DIVISION_BY_ZERO for zero denominator; NUMERIC_RANGE for nonzero input/output rounding to zero or overflow, including delta/average. Rescale. |
branch_policy | not applicable — real principal value only |
tolerance | not applicable — closed form; capability Evidence owns comparison, no global default |
convergence | not applicable — non-iterative |
conditioning | Inverse and change are sensitive near a zero denominator; input rounding differs from arithmetic rounding. No measurement uncertainty propagation. |
rounding | ieee754_round_ties_to_even |
overflow | ieee754_nonfinite_or_coded_error |
reproducibility | deterministic algorithm + Capability@Version |
independent_oracle | Independent CPython Fraction/float; private full corpus, public summary Evidence. |
golden_vectors | Evidence golden + boundary + property (and published_reference_case when listed) |
Declared scope for this capability. Do not use it outside this domain.
Assumptions
One numerical check. The calculator page holds worked steps and FAQ.
20% of 250 = 50
CVP VERIFIED · CVP protocol 1.0.0-proposed · Core assurance. Computational verification is defined by CVP. Supplemental domain review (internal) and named expert review are defined by the Review policy and do not by themselves determine CVP conformance.
Human page, REST, and MCP share the same engine and calculation_version.
Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json
and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 6/6.
curl -sS -X POST 'https://www.calculatorx.com/api/v1/calc/percentage' \
-H 'Content-Type: application/json' \
-d '{"inputs":{"mode":"of","p":20,"x":250},"calculation_version":"1.2.0"}'{
"inputs": {
"mode": "of",
"p": 20,
"x": 250
},
"calculation_version": "1.2.0"
}POST /api/v1/calc/percentage. This is a POST calculate endpoint — do not GET it.
Full REST contract: REST API docs.
Declared calculation modes for this capability.
ofis-whatof-whatchangeadjust-upadjust-downdifferenceHuman-readable sources plus CVP reference evidence classes.
Sources
Derived identities
Reference evidence classes: O1 model · O2 expected_values · O2 numerical_behavior
Inspect, then execute. Same engine as REST and the human calculator.
curl -sS -X POST 'https://www.calculatorx.com/mcp' \
-H 'Content-Type: application/json' \
-H 'MCP-Protocol-Version: 2026-07-28' \
-H 'Mcp-Method: tools/call' \
-H 'Mcp-Name: inspect_capability' \
-d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"math.percentage"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'curl -sS -X POST 'https://www.calculatorx.com/mcp' \
-H 'Content-Type: application/json' \
-H 'MCP-Protocol-Version: 2026-07-28' \
-H 'Mcp-Method: tools/call' \
-H 'Mcp-Name: execute_calculation' \
-d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"execute_calculation","arguments":{"capability_id":"math.percentage","inputs":{"mode":"of","p":20,"x":250},"calculation_version":"1.2.0"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'Pin calculation_version (1.2.0) when the result must stay reproducible.
Inspect the trust tier and required assurance level before execution. Full protocol notes: MCP docs.