Retrieve documents from a MongoDB collection using a query filter. Specify the collection name, optional filter, and result limit to control the output.
Find documents in a collection
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Maximum number of documents to return | |
| filter | No | Query filter (MongoDB query syntax) | |
| collection | Yes | Collection name |
Changes observed during successful MCP inspections.
v1.0.0Does 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, but it only restates the basic purpose. It does not explain that the filter is optional, that limit defaults to 10, what the return shape looks like, or whether the operation is read-only. The description is not misleading, but it provides almost no behavioral detail beyond the name.
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 one short, front-loaded sentence with no filler, which is structurally clean. However, it is under-specified for a tool with three parameters and no annotations; conciseness edges into incompleteness. The sentence earns its place but does not carry enough useful information to be highly rated.
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?
The tool is relatively simple, but with no output schema and no annotations, the description must cover return behavior and selection context. It only states the basic purpose, leaving default-limit behavior, optional filter semantics, and differences from find_one or aggregate unaddressed. This is insufficient for confident tool selection and invocation.
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 baseline is 3 even with no parameter details in the description. The description only mentions the collection as the target and does not add meaning to filter or limit beyond what the schema already documents. This meets the baseline but does not exceed it.
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 ('Find') and a resource ('documents in a collection'), so an agent can tell it returns documents. However, it does not explicitly differentiate from the sibling find_one, and only the plural 'documents' hints that it returns multiple records. It is clear but lacks overt sibling distinction.
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 offers no guidance on when to use this tool versus find_one, count, or aggregate. Sibling tools are listed but never referenced, and no conditions, exclusions, or preferred alternatives are mentioned. An agent must infer usage entirely from the tool name and schema.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.