List Claude Code Models

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, which sets the safety baseline. The description adds useful context: the tool operates against the 'authenticated Claude Code CLI', returns specific data elements (identifiers, resolved models, descriptions, supported effort/mode), and explicitly states it does not run an inference turn. This goes beyond the annotations without contradicting them.

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 two sentences, with the first sentence stating action and scope, and the second summarizing the return content. It is front-loaded with the verb and resource, and every word contributes value without fluff.

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?

Given the tool's simplicity, rich annotations, and presence of an output schema, the description is largely complete: it explains what the tool does, its auth context, and what it returns. It slightly lacks explicit guidance on when to prefer this over run/resume, but that is a minor gap and the 'without running' phrase partially covers it.

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 input schema provides descriptions for all four parameters, giving 100% coverage. The description does not add extra meaning about parameters such as cwd or timeoutMs, but since the schema already handles this, the baseline of 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 description uses a specific verb 'List' and clearly identifies the resource: 'models available to the authenticated Claude Code CLI'. It also distinguishes itself from sibling tools by adding 'without running a model inference turn', making it unmistakably a discovery tool rather than an execution tool.

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 gives clear context: use this tool to list models without triggering inference. However, it does not explicitly mention sibling tools (claude_code_run, claude_code_resume) or state 'use X instead for running models', so it stops short of full exclusion guidance.

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