MCP for IIIF Images

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It describes the tool's process ('fetching info.json and returning the image data scaled to roughly 1M pixels total area'), which adds valuable context about scaling behavior. However, it doesn't mention potential errors, rate limits, authentication needs, or what happens with invalid URIs, leaving some behavioral aspects unclear.

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 a single, well-structured sentence that efficiently conveys the tool's purpose, process, and scaling behavior. Every element earns its place with no wasted words, and the information is appropriately front-loaded.

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 single-parameter tool with no annotations and no output schema, the description provides good coverage of what the tool does and its scaling behavior. However, it doesn't describe the return format (image data type, structure) or error handling, which would be helpful given the absence of output schema. The description is mostly complete but has minor gaps.

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 schema description coverage is 100%, so the schema already documents the single parameter thoroughly. The description doesn't add any additional parameter semantics beyond what's in the schema (base URI format, exclusion of /info.json). This meets the baseline expectation when schema coverage is complete.

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 specific action ('Retrieve'), resource ('IIIF image'), and scope ('from a base URI'). It distinguishes from siblings by focusing on full image retrieval rather than region extraction (fetch_iiif_image_region) or manifest fetching (fetch_iiif_manifest). The description goes beyond just restating the name by specifying the operational details.

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 description provides clear context about when to use this tool ('Retrieve a IIIF image from a base URI') and implicitly distinguishes from fetch_iiif_image_region (which handles regions) and fetch_iiif_manifest (which handles manifests). However, it doesn't explicitly state when NOT to use this tool or name alternatives, keeping it from a perfect score.

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