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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered without the description. The description adds useful substance by enumerating what an evidence record contains (URL, fetch time, SHA-256), which is behavior beyond the annotations, but says nothing about what happens when a field has no evidence or whether records are paginated.

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?

A single compact sentence that front-loads the resource and then the payload fields. No filler, though the colon-list of return fields sits where usage guidance would have been more valuable.

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's enumeration of URL, fetch time, and SHA-256 is genuinely helpful for anticipating the response. However, for a two-required-parameter lookup tool it leaves gaps: no explanation of tool_id provenance, no behavior for missing evidence, and no linkage to the sibling tools that would precede this call.

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 0% with two required parameters, so the description must carry the load. It clarifies that 'field' is a field name, but 'tool_id' is never explained (format, source, or how to obtain it), leaving half the parameters undocumented in both schema and description.

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 identifies the resource (evidence records for a single assertion of a tool) and the keying parameter (field name), but it is phrased as a noun phrase rather than a verb+resource, and it never explicitly says 'retrieve' or 'return'. An agent can infer what it fetches, but the phrasing reads more like a return-value label than a statement of purpose, and it does not differentiate from siblings like get_tool or get_changes.

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?

There is no statement of when to call this versus get_tool, get_changes, or search_tools, and no prerequisites or context are given. The agent must infer from the name alone that this is the drill-down for a specific assertion after inspecting a tool.

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