read_local_image

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It warns that the output can be 'very large and slow to display', which is a meaningful performance trait. It does not explicitly state that the operation is read-only, but 'read_local_image' and 'Read a local image file' strongly imply no side effects.

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 sentences with no filler. The purpose is stated first, followed by the warning and the alternative recommendation, which is well-structured and efficient.

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 simple two-parameter read tool without an output schema, the description covers the core behavior, the performance caveat, and the alternative. It does not cover error cases or supported file formats, but those are not essential given the schema and the straightforward nature of the operation. Slightly more context about when to use data_uri vs base64 could improve it, but it is largely complete.

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 100%, with both file_path and return_format clearly described in the input schema. The description adds the base64 conversion context, but this mostly overlaps with the schema's default value. Since the schema already handles parameter meaning, a baseline of 3 is appropriate.

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 states a specific action ('Read a local image file') and the transformation ('convert it to base64'), making the tool's function immediately clear. It also distinguishes itself from the sibling prepare_image by warning about the large output and recommending the alternative.

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 explicitly names the alternative tool (prepare_image) and gives the condition for choosing it ('for better performance'). This tells an agent when not to use this tool and what to use instead, which is exactly what this dimension requires.

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