Railway MCP Server

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. It effectively indicates this is a creation/mutation tool (implied by 'Create'), specifies use-case constraints (e.g., not for HTTP/HTTPS), and mentions prerequisites and related tools. However, it lacks details on permissions, rate limits, or error handling, which are important for a mutation tool.

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 the core purpose, followed by organized sections (Best for, Not for, Prerequisites, etc.). Every sentence earns its place by providing actionable guidance without redundancy, making it highly efficient and easy to parse.

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 a creation tool with no annotations or output schema, the description does an excellent job covering purpose, usage, and context. It compensates well for the lack of structured fields by providing rich guidance. A slight deduction because it doesn't detail output format or error scenarios, which would be helpful for a mutation tool.

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 the schema already documents all three parameters thoroughly. The description adds no additional parameter-specific information beyond what the schema provides, such as examples or edge cases. This meets the baseline for high schema coverage.

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 specific action ('Create a new TCP proxy') and resource ('for a service'), distinguishing it from sibling tools like domain_create (for HTTP/HTTPS) and tcp_proxy_list (for listing). It explicitly defines the tool's scope and differentiates it from alternatives.

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 explicit guidance with 'Best for' and 'Not for' sections, naming specific use cases (database access, external connections) and exclusions (HTTP/HTTPS endpoints, internal communication). It also lists prerequisites (service_list), alternatives (domain_create), and next steps (tcp_proxy_list), offering comprehensive usage context.

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