image_save

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

Discloses important behaviors beyond annotations: preserves layers/tags/metadata for image_load, streams to disk, file written by server user, ~ expansion, refusal of existing files unless overwrite=True, and the max_bytes cap for in-band mode due to MCP base64 encoding. Annotations only say readOnlyHint=false and destructiveHint=false, so the description adds substantial 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?

The description is information-dense yet well-structured, with a brief opening, a paragraph covering behavior and edge cases, and a clean args list. Every sentence earns its place, avoiding fluff while covering all necessary details.

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?

Given the tool's complexity (two modes, five params, fallback behavior), the description is complete. It covers the archive format, file handling specifics, in-band cap, error case (ValueError), and return types. The output schema exists but the description's return explanation adds clarity.

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?

With 0% schema description coverage, the description fully compensates by explaining every parameter: id_or_name, dest_path (and its omission trigger), named, overwrite, and max_bytes with defaults. It also clarifies return variants for each mode, adding meaning beyond the raw schema.

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 opens with a specific verb+resource: 'Save an image as a tar archive: to a file on the server host, or in band.' It immediately distinguishes itself from container_export, which flattens one container's filesystem, making the tool's unique purpose clear.

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?

Explicitly explains when to use each mode: dest_path for large images with no byte cap, in-band as a fallback when no writable host path exists. It also names the alternative container_export and clarifies how image_save differs, giving clear when-to-use vs. when-not-to-use guidance.

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