select_mcp_or_skills

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

The annotations only declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, and the description adds the mutation semantics beyond that. It states that empty arrays disable a category, that omitted fields preserve the current selection, and that running workers are unaffected. Those behaviors matter for safe invocation. What is still missing is what happens when no arguments are passed, that is, whether that triggers listing mode.

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?

Four short sentences, no wasted words, and the most important constraint, that empty arrays disable a category, comes early. The dual opening 'List available choices, or select...' is slightly ambiguous as a first sentence, but overall the structure is efficient.

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 three-parameter configuration tool with no output schema and no readable annotations, the description covers the selection semantics well. It still leaves the listing mode and the session_id parameter undefined, which are real gaps for an agent trying to call this tool 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 description coverage is 0%, so the schema supplies no meaning for any of the three parameters. The description does explain the semantics of the two array parameters: empty arrays disable a category, and omitted fields keep the current selection. The third parameter, session_id, is never mentioned, and its relationship to the 'running worker' note is left to inference.

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 description gives a concrete verb-and-resource pair: list available choices, or select MCP servers and SKILL.md instructions for new sessions. That is a clear purpose. It does not, however, distinguish itself from the sibling select_model, which follows the same 'select a thing' pattern, so an agent must infer the boundary rather than read it.

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?

'for new sessions' and 'a running worker keeps its configuration' imply scope boundaries. However, the description never states when to invoke listing mode versus selection mode, or whether this is appropriate for mid-session changes. The when-to-use guidance is suggested rather than explicit.

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