sftp-download-file

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

Beyond the destructiveHint annotation, the description reveals important behavior: contents are streamed and not passed through model context, and the tool refuses to operate when transferRoot is not configured. It does not explicitly warn that overwrite=true destroys an existing local file, but that fact is present in the parameter schema, so the description still adds meaningful behavioral context.

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?

Three tight sentences with no filler. The core action and streaming behavior are front-loaded, followed by the restriction and the sibling alternative. Every sentence earns its place.

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 four-parameter download tool with a fully described schema, the description is nearly complete: it covers purpose, streaming, restriction, refusal condition, and when to use the alternative. It does not describe return behavior or explicit overwrite consequences, but these are less critical given the local-disk side effect and the schema coverage.

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 four parameters. The description adds a small amount of extra meaning by explaining the transferRoot constraint and refusal behavior, but it does not materially deepen understanding of individual parameters beyond what the schema provides. Baseline 3 is appropriate.

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 action, resource, and transport ('Download a remote file to local disk over SFTP') and immediately adds a distinguishing trait: 'streaming it without passing the contents through model context.' It also explicitly contrasts with sibling sftp-download, so an agent can tell them apart without inspecting schemas.

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?

Gives clear selection guidance: 'Use this for binary or large files; use sftp-download when you need to read the contents.' It also states a hard prerequisite and failure condition: the destination must be inside transferRoot, otherwise the tool refuses. This is explicit and actionable.

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