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

Annotations declare readOnlyHint=true but also destructiveHint=true, which is internally confusing for a comparison tool; the description usefully resolves the ambiguity by framing this as a read ('Free read') and adds cost/quota context ('Free') that annotations don't convey. It also discloses the return shape at a high level (deltas, changes). No pagination or ordering guarantees, but the behavioral picture is solid.

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 dense sentences: purpose and inputs first, the motivating workflow second. Zero filler, nothing repeated from structured fields.

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?

With no output schema, the description compensates by naming what comes back (score deltas, what changed) and by explaining where the IDs come from and when to run it. Only the ordering requirement and any output limits are left implicit, which the schema's 'Earlier/Later' labels largely cover.

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% and the schema already labels 'before'/'after' as earlier/later snapshot IDs; the description adds only the provenance of those IDs (list_snapshots). Baseline 3 applies since the schema carries the semantic load.

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 verb+resource ('Compare two analysis snapshots') and names the concrete output ('score deltas and what changed'), which cleanly separates it from adjacent tools like get_score_trends or list_snapshots. The parenthetical sourcing hint ('IDs from list_snapshots') removes ambiguity about what inputs it expects.

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?

Gives explicit usage context ('Use after applying fixes — before-run vs after-run proves impact') and points at the sibling that produces the required IDs (list_snapshots). It does not state when NOT to use it or name a competing alternative, so it stops short of a 5.

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