set_skill

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

Annotations only declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the description carries real extra weight: it discloses that level increases require evidence, that the server asks the person to confirm before saving, and that the call returns `saved` and `previous_level`. It does not cover permissions, failure modes, or how existing optional fields behave on a re-set, which keeps it short of a 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 sentences, front-loaded with the core action, then sibling routing, then the behavioral rule and return values. No filler and nothing redundant with the schema.

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 an 8-parameter mutation tool with no output schema, the description supplies the missing pieces: sibling disambiguation, the evidence/confirmation rule, and the return payload. 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 coverage is 100%, so the baseline is 3, but the description adds meaning the schema does not: it explains that evidence gates level raises and that a new skill is treated as rising from X, which clarifies the interaction between the `level` enum and `evidence` across parameters.

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 and resource ('Add or change one skill in the inventory') and immediately delimits scope against two named siblings (set_skills, checklist_apply). An agent can distinguish this single-skill upsert from the batch tools without inspecting any schema.

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?

Explicit routing: use this for a single skill, set_skills for several at once, checklist_apply for a whole marked list. It also gives the conditional rule for evidence (required only when raising a level, including a brand-new skill) and notes that lowering is always permitted.

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