index_skills

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

With annotations declaring readOnlyHint=false but destructiveHint=false, the description resolves the ambiguity: 'Creates Capalith's catalog, never edits sources or activates skills.' That tells the agent exactly what side effect occurs and what does not, which the annotations alone cannot convey. It does not mention failure modes or permission requirements.

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?

Front-loaded with the core action, then compact clauses for each parameter's behavior. Dense but every sentence carries a distinct instruction; the 'config_show previews roots' aside is slightly tacked-on but still useful routing 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?

The tool mutates its own catalog, and the description states the boundary (creates catalog, never edits sources/activates skills) plus the parameter interplays. An output schema exists, so return values need not be explained. Minor gap: no mention of what happens to previously indexed skills on refresh.

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 real meaning: no-arg calls refresh, source_paths is restricted to explicit roots, and host_homes should come from known host context when the environment omitted a value. This clarifies the interaction between optional parameters beyond the per-field schema text.

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?

Opens with a specific verb+resource: 'Find and index installed Codex, Claude Code and current Hermes profile skill directories.' It also distinguishes itself from a sibling by noting 'config_show previews roots,' so an agent can separate indexing from previewing. It stops short of fully differentiating from discover/inspect/traverse, so not a 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?

Explicitly states the invocation modes: no-argument calls refresh the selection, source_paths selects only explicit custom roots, and host_homes is supplied 'from known host context if the client's environment omitted a custom home.' It also notes first-use setup is handled by 'discover.' Clear context with no explicit when-not guidance beyond that.

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