evidence_get_attachment_thumbnail

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

With no annotations, the description must carry the behavioral burden, and it does state the core behavior: downloading a thumbnail to a local file. However, it does not disclose whether an existing output file is overwritten, whether authentication is required, or what happens when the attachment is not an image.

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?

One short sentence expresses the full purpose with no filler. The key resource ('thumbnail'), action ('download'), and destination ('local file') are all front-loaded.

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?

Given the schema fully documents the seven parameters and an output schema exists, the description does not need to explain return values. It is slightly light on usage caveats, but for a download operation the combination of description and schema is mostly sufficient.

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%, so the schema already documents all parameters. The description adds no parameter-level meaning beyond what the schema provides, which matches the baseline of 3.

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 names a specific verb ('Download'), a specific resource ('thumbnail of an image attachment'), and a destination ('a local file'). This clearly separates it from sibling tools like evidence_get_attachment and evidence_download_attachment, which concern full attachments.

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 phrase 'thumbnail of an image attachment' implies the tool should be used when a smaller preview is needed rather than the full attachment, but it never explicitly mentions alternatives or exclusion conditions. Usage context is implied rather than stated.

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