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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds behavioral context beyond annotations by framing this as a recovery re-run, explaining the widget's call pattern, and contrasting it with compare_pdfs. It does not describe edge cases like missing comparisons, but the annotations and output schema reduce the burden.

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?

Three tightly packed sentences: first states purpose, second scopes usage, third gives an alternative. No filler or redundant information. Every sentence earns its place.

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 simple tool with one param, full annotations, and an output schema, the description fully explains what, when, and why. It names the only required input, the trigger scenario, and the preferred alternative, making it complete for an agent to select and invoke correctly.

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 100% with a single parameter (session_id) whose description is self-explanatory: 'Session ID whose latest comparison should be returned.' The description reinforces that only session_id is needed but does not add new semantic detail beyond the schema. Baseline 3 applies.

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 and resource: 'Re-run the most recent PDF comparison for a session.' It clearly distinguishes the tool from its sibling compare_pdfs by noting that this tool only needs session_id, and it is scoped to widget recovery.

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?

Explicitly states when to use: 'For widget recovery only' and describes the triggering condition ('when the host did not hand it the comparison payload'). It also names an alternative and when to prefer it: 'Prefer compare_pdfs when both job_ids are known.'

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