compare_diagnostics

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so 'Read-only; no files are modified' is partly redundant. The description still adds value beyond the structured data with 'deterministic' and 'resilient to line shifts', which are meaningful behavioral traits an agent cannot read off the annotations.

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 tight sentences, front-loaded with the verb and resource, with no filler. The 'Read-only; no files are modified' clause duplicates the annotation and is the only marginally wasteful element.

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?

An output schema exists, so return shape need not be explained, and the description still usefully previews the delta categories (introduced, resolved, unchanged, net delta). For a two-input comparison tool this is nearly complete; only the routing context 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?

Schema coverage is 0%, so the description carries the full parameter burden. It does name both parameters and implies their roles (baselineCheckId = baseline, currentCheckId = current), which is helpful, but adds no format, validity, or ordering semantics beyond what the parameter names already suggest.

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 gives a specific verb ('Computes') and resource ('a deterministic diagnostic delta between two checks'), which clearly separates it from read-oriented siblings like get_diagnostic_snapshot and get_live_diagnostics. It does not explicitly name or contrast against a sibling, so it stops short of a 5.

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?

Usage is implied by the two-check framing (compare a baseline against a current run), but there is no explicit when-to-use, when-not-to-use, or alternative routing guidance. An agent can infer the context but is not steered away from overlapping tools.

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