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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds real behavioral context beyond that: the explicit security guarantee 'Never returns private keys' and the diagnostic behavior 'Explains what to configure if keys are missing'. It stops short of describing rate limits or failure modes, so 4 rather than 5.

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 sentences, each earning its place: what is returned, the diagnostic behavior, and the security guarantee. The primary payload (returned values) is front-loaded.

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?

There is no output schema, so the description carries the burden of describing return values and does so completely (ID, payment address, balance, USD value). Combined with annotations covering the read-only/open-world profile and a fully documented schema, an agent has everything needed to invoke it correctly.

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% and both parameters (fluxIdPrivateKey, paymentPrivateKey) are fully documented in the schema, including guidance to use dedicated keys. The description adds only the vague 'if keys are missing' condition and no syntax or format detail, so the 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 ('Returns') and enumerates the exact resources: Flux ID (app owner address), payment address, spendable FLUX balance and its USD value. It is unambiguous about what the tool produces, though it never names or contrasts a sibling tool, so the 4 rather than 5.

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?

'Explains what to configure if keys are missing' implies a usage context (diagnosing missing/unconfigured keys), which is a useful hint. However, there is no explicit when-to-use statement, no prerequisites, and no alternatives such as flux_generate_keys or flux_get_network_info, so guidance is only implied.

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