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

No annotations are provided, so the description carries the burden. It discloses the tool is a read-only comparison ('diff') and names the compared fields, which implies no mutation. However, it doesn't state the output format, whether it errors on missing iterations, or how it handles identical rules. For a read-only diff tool, the core behavior is clear, but some edge-case behavior is undisclosed.

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 sentences, zero filler. The first sentence defines the operation and scope; the second gives the usage trigger. Every word earns its place, and the key differentiator (structured rules diff) is 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?

For a read-only comparison tool with 100% schema coverage and no output schema, the description covers the purpose, the compared dimensions, and the usage context. The only gap is the lack of detail about the return shape or behavior on missing refs, but since no output schema exists, the description could have said a bit more about what 'diff' returns. Still, the essential information for calling it correctly is present.

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 100%, so the schema already documents all three parameters. The description adds context for ref_a/ref_b by framing them as 'older / baseline' and 'newer', which reinforces the schema's descriptions. The strategy_id parameter's purpose is fully explained in the schema ('routes to that Lab tab, and NO_ACTIVE_LAB errors include a direct Lab URL'), so the description doesn't need to add more. Baseline 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 states a specific verb ('diff') and resource ('structured rules between two @R# iterations'), and enumerates the exact dimensions compared (entry gates per side, position, exit, cooldown). This clearly distinguishes it from sibling tools like patch_entry_gate or select_iteration, which operate on single iterations rather than comparing two.

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 explicitly states when to use the tool: 'Use before adopting an older iteration's levers onto a newer one.' This gives a clear workflow context and implies the alternative (not using it) would risk blind adoption. It doesn't name a specific sibling alternative, but the use case is specific enough that an agent can route correctly.

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