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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), so the bar is lower. The description still adds genuine behavior: it preserves UNKNOWN, abstains when evidence is insufficient, and never authorizes payment or execution, which tells the agent how to interpret partial or missing results.

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, front-loaded with the core purpose, and every clause carries information (scope, constraint handling, uncertainty policy, safety boundary). No filler or restated name/title.

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 tool with a deep nested constraint schema, an executionMode enum, no parameter descriptions, and no output schema, the description is far too thin. An agent cannot know what shape the resolution result takes or what each constraint field means from this text alone.

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 0% across 4 parameters, including a nested constraints object with 13 undocumented sub-fields. The description only alludes to 'constraints' generically and never explains task vs capability, the anyOf requirement, or the SHADOW/ADVISORY/PREFLIGHT executionMode enum, so it fails to compensate for the coverage gap.

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 states a specific action and scope: provider-neutral capability resolution across eligible payment rails, with constraints applied. It implicitly separates itself from phion_execute by declaring it never authorizes payment or execution, but it never names or contrasts with the sibling resolvers (phion_discover, phion_preflight, phion_get_service).

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: 'Advisory only: never authorizes payment or execution' tells the agent this is not the execution path, which hints that phion_execute handles that. However, there is no explicit when-to-use statement and no routing guidance versus phion_discover or phion_preflight.

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