model_config_set

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

With no annotations, the description adequately discloses behavior: it writes to a specific file, explains the effect of an empty string (removing the key), and states the effect scope (new sessions only). This provides sufficient transparency for a configuration 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 a single sentence with a parenthetical detail, front-loaded with the action and resource. Every word adds value, and there is no wasted text. It is highly concise.

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 simple nature of the tool (one parameter, no nested objects, output schema likely trivial), the description covers the key aspects: purpose, mechanism, and side effects. It is complete enough for an agent to use 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 high (100%), but the description adds meaningful context beyond the schema: it explains the effect of empty string and the scope of the change. This improves parameter understanding.

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 clearly states the action 'Set' and the specific resource 'default startup model for new CC sessions'. It distinguishes itself from the sibling tool 'model_config_get' by focusing on writing. The resource is precisely described, avoiding vagueness.

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 provides clear context for when to use (changing default model for new sessions) and notes that it takes effect only on new sessions. While it doesn't explicitly state when not to use or list alternatives, the purpose is well-defined and the scope is clear.

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