save_image

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

Discloses that the return is in-band and capped, with a default limit of 32 MiB. Mentions that exceeding the limit raises a ValueError. These details go beyond the annotations (readOnlyHint, destructiveHint) to explain behavioral constraints.

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 concise and well-structured: a single sentence for the main purpose, followed by a usage sentence and a list of parameters. No redundant or extraneous 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?

Given the tool's complexity (3 parameters, 1 required, no enums) and the presence of annotations, the description covers purpose, usage guidelines, parameter semantics, return type, and error behavior. It is complete and actionable for an AI agent.

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?

The description explains all three parameters: name (image name or id), named (whether to keep the name), and max_bytes (abort if tarball exceeds). This adds meaning beyond the schema which only provides types and defaults, especially since schema description coverage is 0%.

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 clearly states the verb 'save', the resource 'image', and the format 'tar archive'. It distinguishes itself from the sibling tool 'save_image_to_file' by noting that this tool returns in-band and is suitable for small images.

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 says to prefer 'save_image_to_file' for anything but a small image, and explains the reason (in-band returns are capped at 32 MiB due to MCP base64 encoding). Provides clear when-to-use and 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.