opencode_set_model

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

With no annotations, the description carries the burden. It discloses immediate effect and scoping to new sessions, which are meaningful behavioral traits. It omits details like persistence across restarts or permission requirements, but for a simple setter this is adequate.

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, front-loaded with the purpose, and every sentence adds value. No redundancy or irrelevant detail.

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 1-parameter setter, the description explains both the immediate effect and the session scope, while the output schema covers return values. It doesn't mention persistence across restarts, but the tool's behavior is largely clear.

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 schema covers the single 'model' parameter fully with format, examples, and reference to opencode_list_models. The description adds no parameter-specific detail, so a baseline score 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 opens with 'Change the default model used for all new opencode sessions' which uses a specific verb and resource, clearly distinguishing it from sibling session commands like opencode_start_session or opencode_list_models.

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?

It states 'Takes effect immediately for all subsequent opencode_start_session calls. Does not affect already-open sessions,' giving clear timing and scope. However, it does not explicitly name alternative tools or when to prefer them for per-session model selection, so it falls short of full usage guidance.

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