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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's added value is the exact return shape (a <muninn_skills> XML block with name/description/location) and the scope exclusion ('Never another user's'). It does not mention pagination, size limits, or auth requirements, so it stops short of full behavioral disclosure.

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 verb and output format, and each sentence carries a distinct idea (what/scope, how to use the result, when to call). The clauses are densely packed, but no line is filler.

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?

With no output schema, the description compensates by describing the return format and per-item fields. Combined with zero parameters and full annotation coverage, an agent has everything needed to decide when to call this and what it will receive.

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?

The tool takes zero parameters (empty object schema), so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly avoids inventing parameter guidance.

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 (list) and resource (skills saved in Muninn), and immediately scopes the result set: this account's own skills plus built-ins, never another user's. An agent can distinguish it from the skill_create/delete/update/check siblings without opening 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?

Gives explicit when-to-use ('mid-session, for example right after they create one') and when-to-consult-a-skill ('when the user's request matches it'), plus the concrete follow-up (open instructions via muninn_memory_get using the id at the end of the location). That is a full routing path, not just a context hint.

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