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

Annotations already establish readOnlyHint=true and openWorldHint=true, so the safety profile is covered; the description adds genuine value on top by disclosing the network-dependent phase, the specific checks performed (image reachable, architecture, ports, name availability), and the success return (node-formatted spec). It stops short of saying what happens on failure or clarifying that nothing is registered.

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?

Two sentences, zero waste, and the two-phase sequence is front-loaded before the return behavior. Every clause carries information.

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 nested, key-accepting tool with no output schema, the description covers the process and result adequately, and annotations cover safety. It leaves minor ambiguity about failure behavior and whether any registration side effect occurs, which is slightly more important given the tool accepts payment and identity private keys.

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 75%, so the schema already documents most parameters, including the private-key handling conventions. The description's check list (architecture, ports, name availability) loosely maps to spec fields but adds no new syntax or constraint detail. Baseline 3 is appropriate.

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?

The description names a specific verb+resource ('validate a specification') and describes the two-phase behavior (local rule checks then node verification). It distinguishes the tool's intent from write-path siblings like flux_deploy_app by stressing it behaves 'exactly as it would at registration,' but it never names an alternative tool outright.

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?

Usage is only implied: an agent can infer this is a pre-deployment gate from 'exactly as it would at registration,' but there is no explicit when-to-use framing, no statement of the condition that selects it over flux_build_spec or flux_quote_app, and no mention of prerequisites.

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