open_image

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

Annotations indicate readOnlyHint: false (not read-only) and destructiveHint: false (not destructive). The description adds context about verifying path existence but does not disclose potential side effects such as changing the active window, memory usage, or handling of unsupported file formats. With the annotations already providing safety profile, the description adds some but not rich transparency.

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 consists of two sentences, the first stating the purpose and the second providing a key usage guideline. It is front-loaded and free of extraneous information, making it efficient and clear.

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 simplicity (one parameter, output schema exists, annotations present), the description covers the main purpose and a critical precondition. However, it could better differentiate from sibling tools like 'list_open_images' or 'get_image_info', but the presence of an output schema reduces the need to explain return values. The overall completeness is high for this tool.

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 coverage is 100%, with a detailed description and examples for the 'path' parameter. The description adds value by instructing to verify path existence, which goes beyond the schema. This justifies a score above the baseline of 3.

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: 'Open an image from disk in Fiji and show it as the active window.' It identifies the verb (open), resource (image), and distinguishes it from sibling tools like 'list_open_images' (which lists already open images) and 'save_image' (which writes to disk).

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 includes a precondition: 'Verify the path exists on the MCP host before calling.' However, it does not provide guidance on when to use this tool versus alternatives (e.g., if the image is already open, use 'list_open_images'), nor does it specify exclusions or alternative contexts. The guidance is minimal but present.

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