Can the character use this?

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

With no output schema, the description carries the burden of explaining results and does so well: prerequisite skills, missing levels, SP required, estimated training time derived from character attributes, and a training order. Annotations already cover the read-only and open-world nature, so remaining value is in the output content, which is covered.

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, front-loaded with the core check and followed by the result contents. No filler; slightly dense but 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?

Covers all three parameters and the return content in the absence of an output schema. One minor gap: with zero required parameters, it does not say what happens if neither eft nor items is supplied, nor what takes precedence if both are.

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%, so the schema already documents eft, items, and characters. The description only restates the shapes (items or a whole fit, compare several characters) without adding format, limit, or precedence details beyond the schema.

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 (checks) and resource (items or an EFT fit) and enumerates the item categories covered (ships, modules, ammo, drones). It is clearly distinct from character_skills in spirit, but the description never names or contrasts a sibling, so sibling differentiation is left implicit.

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?

Gives clear context: use it to validate items or a whole fit, and to compare several characters in one call. There are no explicit when-not conditions or named alternatives, but the intended usage is unambiguous.

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