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

Annotations already provide readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds meaning by limiting scope to 'readable stored evidence' and clarifying that it returns counts and evidence-presence indicators rather than full history. This is useful context beyond the annotations, though it omits details like response shape or pagination.

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 with zero filler. The first sentence states the action, scope, and expected output; the second is a crisp exclusion. Information is front-loaded and every word 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 read-only summarization tool the description is clear, but it lacks an output schema and does not explain the shape of the response beyond vague categories. With 12 parameters and many filters, the description could benefit from noting how filters combine or what the result structure looks like.

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 58%, and many parameters have detailed schema descriptions (date_from/to, chain_ids, asset_type, multichain, evidence_class, exclude_post_types). The tool description adds no extra parameter-level information; its mention of 'fixture/embedded evidence' and 'engagement-checkpoint presence' maps to existing schema concepts. Baseline 3 applies because the schema carries the documentation burden.

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 uses a specific verb ('Describe') and resource ('readable stored evidence in a required UTC window'), and enumerates output categories (counts, fixture/embedded evidence, engagement-checkpoint presence). It differentiates by stating what it is not (complete source history or live collection watermark), though it does not explicitly name sibling tools.

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 conveys when to use the tool (for a high-level description of archived evidence in a time window) and provides an explicit when-not ('Not complete source history or a live collection watermark'). It lacks named alternative tools, so it stops short of a full 5.

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