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

Annotations mark this as a non-read-only, non-destructive, non-open-world write. The description adds useful behavior context: the appearance of the item depends on file type, and the two accepted sources for file content. It does not mention permissions, limits on file size, or what happens if the upload name is stale.

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, front-loaded with the main effect and followed by the source-of-file rule. No filler, though the second sentence compresses two alternatives into one clause without fully separating the cases.

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 6-parameter write tool with no output schema and no output described, the definition covers what the agent most needs: what gets created, how it looks, and where the file content comes from. Missing are error cases and whether an upload name expires, but those are beyond the typical scope of a description.

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 83%, so most parameters are already documented. The description still adds value by explaining the semantic difference between 'upload' (name returned by upload_file) and 'data' (raw base64 for small files), which is the key decision for the agent. It does not explain the coordinate behavior of x and y beyond the schema's own 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 uses a concrete verb and resource ('Put an image or a document on a board') and explains the observable result: images render as pictures, documents render as file objects others can open and download. This distinguishes it from siblings like add_block or upload_file.

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 tells the agent that the file must come as an upload name from upload_file, or as base64 bytes for a small file. That implies a workflow with upload_file, but it does not state when to prefer base64 over an upload URL or when to use add_block instead.

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