evidence_thumbnail_url_get

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

Annotations already indicate readOnly and nondestructive behavior; the description adds meaningful behavioral context: the URL is temporary, it is for thumbnails only, and it avoids downloading the original. This goes beyond the structured safety hints without contradicting them.

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?

The description is brief and front-loaded with the core purpose in the first sentence, followed by requirements. However, the naming error ('evidenceGroupId' vs 'groupId') slightly undermines its otherwise efficient structure.

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?

While a simple read tool with output schema and safety annotations, the description is not fully complete: the parameter naming inconsistency could cause invocation errors, and thumbnailSize semantics are unexplained. These are material gaps for correct usage.

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 only 50%, and the description must compensate but fails to do so adequately. It lists 'caseFileId + evidenceGroupId + evidenceId', but the actual schema parameter is 'groupId', creating a naming mismatch. It adds no meaningful detail for 'thumbnailSize' (e.g., accepted values), leaving two parameters under-described.

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 clearly states the tool retrieves a temporary thumbnail URL for image evidence, specifying the exact verb and resource. It distinguishes itself from sibling download URL tools by emphasizing 'thumbnail' and 'without downloading the original file', making the purpose unambiguous.

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 says 'use for quick visual verification without downloading the original file', providing clear context. It also notes 'image-type evidence only', which sets a boundary, though it does not name alternative tools for other use cases.

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