Marlo MCP

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 but fails completely. It doesn't indicate whether this is a read-only operation, what data format to expect, whether there are rate limits or authentication requirements, or what happens on errors. 'get market rates' implies data retrieval but provides zero insight into how that retrieval behaves or what constraints exist.

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?

While technically concise with only two words, this description suffers from severe under-specification rather than effective brevity. It doesn't front-load important information or structure content meaningfully—it's just the bare minimum restatement of the tool name. True conciseness would efficiently convey purpose and context, which this lacks entirely.

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 complexity implied by 'market rates' in a financial/shipping context and the absence of both annotations and an output schema, the description is completely inadequate. It doesn't explain what data is returned, in what format, or under what conditions. For a tool that presumably returns important financial data, this minimal description leaves the agent guessing about fundamental aspects of the tool's operation and output.

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 tool has zero parameters (parameter count: 0), and the schema description coverage is 100% (though with no parameters to describe). The description doesn't mention parameters, which is appropriate since none exist. A baseline score of 4 is warranted because there are no parameters whose semantics need explanation beyond what the schema already provides (which is nothing, correctly).

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 'get market rates' is essentially a tautology that restates the tool name without adding meaningful context. It doesn't specify what market rates are being retrieved (e.g., interest rates, commodity prices, shipping rates) or what format the data comes in. While it does contain a verb ('get') and resource ('market rates'), it's too vague to distinguish this tool from siblings like 'get_interest_rates' or 'get_vessel_valuation' that might also involve rate data.

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 absolutely no guidance about when to use this tool versus alternatives. It doesn't mention any prerequisites, context for usage, or relationships to sibling tools like 'get_market_rate_details' (which might provide more granular data) or 'get_interest_rates' (which might be a subset). The agent receives no help in determining appropriate scenarios for this tool's invocation.

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