Marlo MCP

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 only states the action ('list all') without any information about permissions required, rate limits, pagination, output format, or whether it's a read-only operation. For a tool with zero annotation coverage, this is a significant gap that leaves the agent guessing about critical behavioral traits.

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 extremely concise ('list all vessel fixtures') but arguably under-specified rather than efficiently informative. While it uses minimal words, it lacks necessary context that would make it truly helpful. It's front-loaded in the sense that it's only one phrase, but that phrase doesn't earn its place by adding value beyond the tool name.

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 of listing operations (often involving pagination, filtering, or sorting), no annotations, and no output schema, the description is incomplete. It doesn't address what the output contains, how results are structured, or any limitations. For a tool in a domain with many sibling tools, more context is needed to guide the agent effectively.

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 0 parameters, and the input schema has 100% description coverage (though empty). The description doesn't need to explain parameters, and it correctly doesn't mention any. A baseline of 4 is appropriate since there are no parameters to document, and the description doesn't misleadingly suggest otherwise.

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 'list all vessel fixtures' is a tautology that essentially restates the tool name without adding meaningful clarification. It specifies the verb 'list' and resource 'vessel fixtures' but lacks detail about what vessel fixtures are or the scope of 'all' (e.g., unfiltered, across all time). Compared to siblings like 'get_vessel_fixture_details' or 'get_vessel_fixture_contacts', it doesn't clearly differentiate beyond implying a broader listing function.

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 no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites, context (e.g., for reporting or overview purposes), or exclusions. Given siblings like 'get_vessel_fixture_details' (for specific items) and 'get_vessel_fixture_contacts' (for related data), the lack of comparative guidance leaves the agent to infer usage based on naming alone.

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