opencode_session_diff

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

Annotations already declare readOnlyHint=true and idempotentHint=true, providing safety context. The description adds the return format (success/message/data with diff dict) and states that it returns a summary with file paths and change types. This goes beyond annotations without contradiction, though it does not describe error cases or edge behaviors.

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 well-structured: purpose first, then return format, then example. Every sentence earns its place, though the return format block is slightly redundant given the output schema exists. Overall, it is appropriately sized and front-loaded.

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 (1 parameter, read-only, annotated as safe), the description covers purpose, return format, and provides an example. It misses potential edge cases (e.g., nonexistent session) and detailed diff structure, but the output schema likely covers return values, so it is reasonably complete.

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 already provides 100% coverage for the single parameter (session_id with description 'Session ID to diff'). The description's example only demonstrates usage, adding no additional meaning or constraints beyond the schema. Baseline of 3 applies due to high schema coverage.

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 a specific verb+resource: 'Show files created, modified, and deleted in a session.' This clearly distinguishes the tool from siblings like opencode_get_session (which likely retrieves session info) and opencode_send_message. The scope is explicit and unambiguous.

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 implies usage (when you need a diff of session changes) but does not explicitly state when to use it vs. alternatives like opencode_get_session or opencode_get_messages. There is no mention of exclusions or contexts where this tool is inappropriate. The example shows invocation but no guidance on selection.

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