QC-004 QPE. Presented phase must equal k/2^m exactly. m<=8. Floats refused.
| Name | Required | Description | Default |
|---|---|---|---|
| k | Yes | eigenphase index, 0 <= k < 2^m, decimal, e.g. 1 | |
| m | Yes | precision bits, 1..8, e.g. 2 | |
| phase | Yes | the presented phase as an exact rational num/den, must equal k/2^m, e.g. 1/4 for m=2, k=1 |
Changes observed during successful MCP inspections.
Input schema / properties / k / descriptionAdded value: +"eigenphase index, 0 <= k < 2^m, decimal, e.g. 1"Input schema / properties / m / descriptionAdded value: +"precision bits, 1..8, e.g. 2"Input schema / properties / phase / descriptionAdded value: +"the presented phase as an exact rational num/den, must equal k/2^m, e.g. 1/4 for m=2, k=1"Input schema / requiredPrevious value: -[]New value: +[
+ "k",
+ "m",
+ "phase"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose two behavioral traits beyond restating the name: the exactness requirement, the m<=8 bound, and refusal of floats. However, it omits what happens on failure (error vs. false/negative result), whether the tool is read-only, and any return-shape signal.
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?
Three short telegraphic sentences with no filler; the core contract ('must equal k/2^m exactly') is front-loaded after the identifier. Nothing to cut.
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 3-required-param verification tool with no annotations and no output schema, the description covers the input contract but omits the failure semantics (what 'refused' means as a response) and the positive/negative result shape, which is the tool's entire purpose.
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 100% – the k, m, and phase parameters are each documented with constraints and examples in the schema. The description adds the global m<=8 constraint and the exact-equality relation linking the three params, but no syntax or format detail beyond the schema; baseline 3 applies.
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 (verify) and resource (QP phase), and pins the conceptual scope to 'QPE' (quantum phase estimation). It does not name a sibling or differentiate itself from the many other verify_* tools, but the domain specificity keeps it from being vague.
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 implies usage through the exact-equality contract ('Presented phase must equal k/2^m exactly'), but never states when to use this vs. e.g. verify_phase_kickback or verify_qft_phases among the crowded verify_* family, nor does it state prerequisites or exclusions.
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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