generate_er_diagram

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

No annotations are provided, so the description carries the full burden. It implies a read-only operation (generating a diagram) and indicates the source (foreign key relationships), which is useful. However, it doesn't disclose potential limitations (e.g., missing foreign keys, empty result) or explicitly confirm no side effects, though 'generate' strongly suggests non-mutating behavior. This is adequate but not exhaustive.

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 a single, concise sentence that front-loads the core action ('Generate') and object ('Mermaid ER diagram'), followed by the source. It contains no fluff or redundancy, and the structure is optimal for quick comprehension.

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—three optional parameters, no output schema, no nested objects—the description is reasonably complete. However, it doesn't mention edge cases (e.g., behavior when no foreign keys exist) or explicitly state the output format (though 'Mermaid ER diagram' implies text). It also doesn't note that parameters are optional and defaults are used. While functional, it lacks a few details an agent might need for confident 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 all three parameters (schema, server, database) are already documented in the schema. The description adds no additional meaning or syntax details beyond what the schema provides. Per the baseline for high coverage, a score of 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?

The description clearly states the tool's function: generating a Mermaid ER diagram based on database foreign key relationships. It uses a specific verb ('Generate') and resource ('Mermaid ER diagram'), and the source is explicit. While it doesn't mention sibling differences, the purpose is distinct enough that an agent can infer when it applies, differentiating from tools like get_foreign_keys (which lists relationships) or compare_schemas (which compares).

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?

No usage guidance is provided. The description doesn't specify when to use this tool over alternatives, nor any exclusions or prerequisites (e.g., 'Use this when you need a visual representation of relationships'). It only states what it does, leaving the agent to infer applicability.

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