Identify objects in an image and return their bounding boxes. Optionally specify what to find via a prompt.
Detect objects in an image and return bounding boxes. Uses Gemini for native bounding box support. Coordinates are normalized 0-1000 as [ymin, xmin, ymax, xmax].
| Name | Required | Description | Default |
|---|---|---|---|
| image | Yes | Path to the image file or URL (http/https) | |
| prompt | No | Optional: what to detect (e.g., 'find all buttons', 'detect UI elements') |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does well by disclosing the output format: normalized 0-1000 coordinates as [ymin, xmin, ymax, xmax]. It doesn't disclose error behavior (e.g., if no objects found), rate limits, or auth requirements, but the coordinate format is crucial and beyond schema.
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?
Three dense sentences, zero waste, front-loaded with purpose immediately followed by technology and output format. Every sentence earns its place.
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 no output schema, the description appropriately details the return value (bounding boxes and coordinate format). Missing are any behavioral traits like what happens when no objects are found or whether multiple objects are returned, but overall it is complete enough for an agent to invoke and interpret.
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%, so the schema fully documents both parameters including examples for the prompt. The description adds no parameter meaning beyond what the schema provides, so baseline 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?
States a specific verb (detect) and resource (objects in an image) with the return artifact (bounding boxes). It doesn't differentiate from siblings like describe or describe_region, which also extract information from images, leaving the agent to infer when detection is preferable to description.
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 mention of 'native bounding box support' via Gemini implies usage for spatial detection, but there is no explicit when-to-use guidance or comparison to siblings like describe_region (which may also locate regions). No when-not-to-use or alternatives are provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.