list-drive-item-thumbnails

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds behavioral details beyond that: the return is nullable, returns empty for unsupported types, and URLs are short-lived. These are useful and not redundant with annotations. It doesn't contradict annotations and adds context about the output lifecycle.

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 compact: a definition sentence plus a tip block. It repeats some information (the definition says "Collection of thumbnailSet objects" and the tip restates "Lists thumbnail sets"), but the tip adds new practical details. It's front-loaded with the purpose and keeps guidance efficient.

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 list operation with standard OData query parameters, the description covers the essential behavior: what it returns, how to narrow results, and edge cases. It doesn't elaborate on pagination semantics, but the schema parameters (top, skip, fetchAllPages) handle that. No output schema exists, so the description's coverage of the return shape (thumbnail sizes) is adequate.

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 parameters are well-documented. The description adds value by giving concrete examples for $select and $expand (e.g., $select=small,medium,large) and explains the thumbnail sizes available, which helps the agent form correct queries. This goes beyond the schema's generic descriptions.

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's function: "Lists thumbnail sets for a file" with specific details on the thumbnails (small, medium, large sizes, URL and dimensions). It distinguishes from siblings like get-drive-item by focusing exclusively on thumbnail sets, and even notes the behavior for unsupported types (text docs). This is a specific verb+resource definition, not a tautology.

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 provides clear usage guidance: how to request specific sizes via $select or $expand, and warns that URLs are short-lived. It also implicitly advises against using this for text docs by stating it returns empty. However, it doesn't explicitly name alternative tools for non-thumbnail needs or draw comparisons to siblings like list-drive-item-versions. Still, the context is sufficient for an agent to know when to call it.

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