sandbox_upload

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

Annotations already declare destructiveHint=true and openWorldHint=false, so the safety profile is partially covered. The description adds real context beyond them: a hard 4 MiB size cap and the fact that content goes into the guest filesystem rather than reading from a host path, which are concrete operational constraints not present in the schema or annotations.

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 short sentences, zero filler, with the size limit and destination front-loaded and the input-type caveat kept as a compact trailing clause. Every clause carries information.

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 mutation tool with no output schema and 0% schema coverage, the description is thin: it omits whether an existing file at the target path is overwritten, how 'path' relates to the hardcoded C:\work destination, and what a successful call returns. The annotations at least carry the destructive flag, so the gap is partial rather than total.

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 must compensate and it only partly does: it clarifies that data is bytes (base64 payload) and that the target is a guest path, not a host path. However, it never resolves what the 'path' parameter means relative to the stated fixed destination C:\work, leaving the most important parameter ambiguous.

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?

States a specific verb (Upload) and resource (bytes into the guest's C:\work directory), which is clearly distinguishable from the sibling sandbox_download. It stops short of explicitly naming the sibling/alternative, but the directionality makes the intent unambiguous.

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 constraints 'at most 4 MiB' and 'input is bytes, never a host path' implicitly tell the agent when this tool applies versus a host-side write, but there is no explicit when-to-use/when-not guidance or named alternative tool. Usage is implied rather than directed.

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