Draw.io MCP Server

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 states the tool 'creates an edge,' implying a write/mutation operation, but doesn't describe side effects (e.g., whether it overwrites existing edges), permissions needed, error conditions, or what happens on success/failure. For a mutation tool with zero annotation coverage, this is a significant gap in transparency.

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, efficient sentence that front-loads the core purpose. It avoids redundancy and wastes no words, though it could be slightly more structured (e.g., by explicitly noting it's for creation versus editing). Every part earns its place, making it concise and clear.

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 complexity (a mutation operation with 4 parameters, no annotations, and no output schema), the description is incomplete. It lacks details on behavioral traits (e.g., idempotency, error handling), output format, or how it fits with siblings like 'edit-edge'. For a tool that modifies data without structured safety hints, more context is needed to guide proper usage.

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%, with clear descriptions for all parameters (source_id, target_id, text, style). The description adds minimal value beyond the schema, only implying that parameters relate to 'vertexes (cells)' without detailing syntax or constraints. With high schema coverage, the baseline score of 3 is appropriate, as the description doesn't significantly enhance parameter understanding.

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 purpose: 'creates an edge, sometimes called also a relation, between two vertexes (cells).' It specifies the verb ('creates'), resource ('edge'), and clarifies terminology ('relation', 'vertexes/cells'). However, it doesn't explicitly differentiate from sibling tools like 'edit-edge' or 'set-cell-data', which could involve edge modifications.

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 (e.g., existing cells), exclusions, or comparisons to siblings like 'edit-edge' (for modifying edges) or 'add-cell-of-shape' (for adding other elements). Usage is implied but not explicitly stated.

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