List databases

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

The description adds significant behavioral detail beyond the readOnlyHint annotation: it discloses the exact JSON return format, instructs the agent to never mention the tool's name, defines card vs. Markdown rendering rules, and specifies skipping system schemas unless asked. These are concrete behaviors that aid invocation and response formatting, going well beyond the annotation.

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 well-structured and front-loaded with purpose, then usage, then return format, and finally presentation/formatting. Every sentence contributes essential information for the agent to act correctly, including rendering details that would otherwise be missing. Nothing is redundant or verbose relative to the tool's needs.

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 tool's simplicity (no required parameters) and the existence of an output schema (as indicated in context signals), the description is complete: it explains the purpose, when to use, the return shape, how to present results, and formatting exceptions. There are no gaps that would prevent an agent from using the tool 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 input schema already contains a complete description of the single optional parameter `db_id`, achieving 100% schema coverage. The tool description does not add further parameter-level context; it only implicitly references the default connection when omitting the parameter. Per the rubric, a 3 is the baseline when schema covers all parameters, and no extra semantics are provided.

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 opens with a specific verb-resource statement: 'List all databases visible to the configured MySQL account.' This clearly distinguishes the tool from siblings like list_tables or describe_table, which target tables or schemas. It also uses the synonym 'schemas' to remove ambiguity, making the purpose absolutely clear.

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 second sentence explicitly states when to use: 'Use this tool when the user wants to know which databases (schemas) exist on the server.' It gives clear context, though it does not name exclusionary conditions or direct users to alternative sibling tools for other intents. That keeps it a 4 rather than a 5.

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