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RunOnFlux

Flux Cloud MCP server

Official
by RunOnFlux

Build a Flux app specification from a simple description

flux_build_spec

Build a complete v8 Flux app specification from images, ports, resources, and term. Auto-picks public ports, enables data replication, and returns local validation errors and warnings.

Instructions

Turns images, ports, resources and a term into a complete, correctly formatted v8 specification, with public ports auto-picked and data replication enabled. Returns the spec plus local validation errors and warnings.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
nameYesUnique app name: letters, digits, inner hyphens. Not starting with "flux" or "zel".
nodesNo
monthsNoTerm in network months (88000 blocks each). Default 1.
contactsNo
staticipNo
instancesNoCopies on distinct nodes. Default 3.
componentsYes
descriptionNo
geolocationNo
expireBlocksNoExact term in blocks; overrides months.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.1

TDQS

B3.3/5.0
Behavior3/5

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

With no annotations, the description carries the full disclosure burden, and it does add real behavior: public ports are auto-picked and data replication is enabled by default. It also states the return content (spec plus local validation errors and warnings). It omits whether the tool has any side effects or persistence (build vs. deploy), which is the key behavioral question for this sibling family.

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

Conciseness5/5

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

Two sentences, front-loaded with the core transformation and followed by the auto-fill/return behavior; no filler or redundancy.

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

Completeness3/5

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

For a 10-parameter tool with no annotations and no output schema, the description covers the return value well but leaves most parameters and the build-vs-deploy relationship unexplained. It is minimally adequate rather than complete.

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 only 40% across 10 parameters, so the description should compensate more than it does. It loosely maps to components/images, ports, resources, and 'a term' (months/expireBlocks), but says nothing about name, instances, nodes, contacts, staticip, geolocation, or per-component env/commands/dataPath.

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?

The description names a specific transformation ('turns images, ports, resources and a term into a complete, correctly formatted v8 specification'), so the verb and output artifact are unambiguous. It does not, however, distinguish itself from siblings like flux_validate_spec or flux_quote_app, which an agent must choose between in the same workflow.

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?

There is no explicit when-to-use guidance, no mention of prerequisites, and no routing to or away from flux_validate_spec, flux_quote_app, or flux_deploy_app. The only signal is the implied 'build before you deploy' ordering, which the agent must infer.

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