Discover tools and skills

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description's 'Read-only and idempotent' reinforces rather than adds. However, it adds non-annotation context with 'Auth: gate', which is important operational behavior for an agent to know before invoking the tool.

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?

The description is compact and well-structured: core purpose first, then usage timing, exclusions, and safety/auth flags. Every sentence contributes essential information with no filler or redundant elaboration.

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 simple tool with one optional parameter and an output schema, the description fully covers when to use it, what it lists, what it does not do, and the auth requirement. There are no meaningful gaps that would prevent correct invocation.

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%, and the query parameter is fully described as an optional case-insensitive substring filter on name or kind. The description only restates 'optionally filtered by a substring query' and does not add new parameter-level meaning, so the baseline 3 is appropriate.

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 first sentence states a specific verb ('List') and resource ('this kernel's MCP tools and loaded Agent Skills'), making the core function immediately clear. It also distinguishes itself from closely related siblings by explicitly naming a2a_card and skills_list, so an agent can select it without opening schemas.

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?

The description explicitly says when to use it ('at session start or when unsure which tool to call') and when not to use it ('Do not use to fetch the A2A interoperability card' or 'skill bodies'), naming the alternatives. This is clear, actionable routing guidance.

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