Railway 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. It implies this is a read-only operation by listing 'Best for' scenarios like viewing and auditing, but doesn't explicitly state whether it's safe, requires authentication, or has rate limits. The description adds some context about listing shared variables when serviceId is omitted, but lacks details on output format or pagination.

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, Prerequisites, Next steps, Related). Every sentence adds value without redundancy, making it efficient and easy to scan.

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 moderate complexity (listing variables), no annotations, and no output schema, the description does a good job covering usage context, prerequisites, and related tools. However, it lacks details on behavioral aspects like authentication needs or output format, which would be helpful for a tool with no structured output schema.

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. The description doesn't add any parameter-specific details beyond what's in the schema, such as clarifying the relationship between environmentId and serviceId. Baseline 3 is appropriate when the schema provides complete parameter documentation.

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 verb ('List') and resource ('all environment variables for a service'), making the purpose specific and unambiguous. It distinguishes this tool from sibling tools like variable_set or variable_delete by focusing on listing rather than modifying variables.

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' scenarios (viewing configuration, auditing, checking connection strings), prerequisites (service_list), next steps (variable_set, variable_delete), and related tools (service_info, variable_bulk_set). This comprehensively covers when to use this tool versus alternatives.

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