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Overwrite a quantity (DVA)

cm_dva_write

Overwrite a quantity during a run to adjust simulation parameters via Direct Variable Access.

Instructions

Overwrite a quantity during a run via Direct Variable Access.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
modeNoAbsolute value, offset or factor; Ramp variants blend inAbs
nameYesQuantity to overwrite, e.g. 'DM.Gas'
valueYesValue, offset or factor, depending on mode
duration_msNoHow long the override lasts in ms (-1: until released or the run ends)

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

C2.9/5.0
Behavior2/5

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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, and the description's 'overwrite' is consistent with that. However, it adds essentially nothing beyond the annotations and the schema: no statement about run-scoped lifetime, whether the override persists until released, or whether it can be applied to unknown quantities.

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?

One front-loaded sentence with no filler and no redundancy. It is efficient, though arguably too terse given the tool's stateful side effects.

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

Completeness2/5

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

An output schema exists, so return values need not be explained, but the description omits the critical operational context that this override typically must be undone via cm_dva_release (signalled by duration_ms defaulting to -1). For a mutation tool in a family with a dedicated release sibling, that omission leaves an agent without enough to use it correctly.

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

Parameters3/5

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

Schema description coverage is 100%, so the schema already documents mode, name, value and duration_ms in detail. The description adds no parameter meaning beyond that, which is the expected baseline when the schema does the heavy lifting.

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

Purpose4/5

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

States a specific verb and resource (overwrite a quantity) plus the mechanism (Direct Variable Access) and timing (during a run). It is clear what the tool does, but it never names the counterpart cm_dva_release or cm_standalone_dva_write, so sibling differentiation is left to inference.

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

Usage Guidelines2/5

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

No when-to-use guidance, no prerequisites tier (e.g. requires an active run/session), and no mention of the paired release tool. The only timing information is implicit in the words 'during a run'.

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