session_set_model

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

Annotations only say non-read-only and non-destructive, so the description must carry behavior details. It adds that support is conditional ('when supported') and that OpenCode accepts providerID/modelID, but it doesn't disclose failure modes, side effects, or permission requirements. That's minimal but non-contradictory.

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?

Two short sentences with no filler and the primary action front-loaded. The second sentence is somewhat cryptic ('OpenCode accepts providerID and modelID') but still 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?

Three required parameters and no output schema, yet the description gives only a two-sentence overview. It doesn't specify which provider values are valid (schema does), what the model object shape is beyond a hint, or what a successful change returns. For a non-read-only tool, this is thin.

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?

With 0% schema description coverage, the description needed to explain provider, nativeId, and model. It hints that nativeId identifies the exact native session and that opencode uses providerID/modelID, but it never explains the string vs object forms of model or the provider enum. Partial compensation at best.

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?

States a specific action ('Change the model') and a specific target ('an exact native session'), which separates it from generic model-setting tools. The 'when supported' caveat and the OpenCode note add useful context. It doesn't explicitly name sibling tool set_model, but the 'native session' qualifier makes the scope clear.

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?

No explicit guidance on when to use this tool over siblings like set_model, session_resume, or session_create. The only condition is 'when supported', which is too vague to route an agent. There are no exclusions or alternative tool names.

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