download_file

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

The annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, and the description is consistent with them by framing the tool as a local write. It adds useful context that the write target is the user's own machine rather than Canvas, but it omits important behavior: whether an existing file at destination_path is overwritten, whether parent directories are created, and whether large files are streamed or size-limited.

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 purpose statement is front-loaded in a single sentence, and the Args/Returns blocks are compact and each line earns its place. The docstring-style formatting is slightly mechanical but does not add waste. Nothing is buried or repeated.

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 two-parameter write tool this covers the essentials, and an output schema exists so the description's Returns line is supplementary rather than load-bearing. However, the absence of any overwrite/error behavior and of routing guidance against the many sibling file tools leaves real gaps for a mutating, open-world operation.

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%, so the description carries the full burden, and it does: file_id is identified as a Canvas file ID and destination_path as an absolute local path. The absolute-path requirement is genuinely useful meaning not present in the schema. It does not clarify whether the path must already exist or whether it may point to a directory, which keeps it below a 5.

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 first sentence states a specific verb and resource ('Download a file') plus the target location ('to a local path on the user's machine'), which is enough for an agent to distinguish it from read-only siblings such as get_file or fetch_file_content. It stops short of naming those siblings explicitly, so the differentiation is implied rather than stated.

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 guidance on when to use this tool versus the several file-related siblings (get_file, fetch_file_content, canvas_read_file, canvas_browse_files). The description never says, for example, that this is the tool for persisting bytes to disk while fetch_file_content returns content inline. An agent must infer the choice from the name alone.

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