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 does well by indicating this is a creation/mutation tool ('Create a new domain'), mentioning prerequisites (service_list, domain_check), and suggesting next steps (domain_update). However, it doesn't disclose potential side effects, error conditions, or what happens when domain/suffix/targetPort are omitted despite them being optional in the schema.

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 efficiently structured with clear sections using icons and bullet points. Every sentence earns its place: the core purpose is stated upfront, followed by organized guidance. No wasted words while maintaining excellent readability through visual formatting.

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?

For a creation tool with 5 parameters, 100% schema coverage, but no annotations or output schema, the description does quite well. It covers purpose, usage guidelines, prerequisites, and relationships to other tools. The main gap is lack of information about what happens after creation (response format, success indicators) since there's no output schema, and it doesn't address potential errors or constraints beyond the basic guidance.

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 baseline is 3. The description adds value by contextualizing the optional parameters: it implies that railway will generate domain/suffix automatically and detect targetPort, which helps the agent understand when to provide these vs. rely on defaults. However, it doesn't explain the relationship between environmentId and serviceId or provide examples of valid domain formats.

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 with specific verb+resource: 'Create a new domain for a service.' It distinguishes from siblings by explicitly mentioning what it's not for (TCP proxy setup, internal service communication) and naming alternatives like tcp_proxy_create. This provides excellent differentiation within the toolset.

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 comprehensive usage guidance with explicit sections: 'Best for' lists three specific use cases, 'Not for' excludes two scenarios with named alternatives, plus 'Prerequisites', 'Alternatives', 'Next steps', and 'Related' tools. This gives the agent clear when-to-use and when-not-to-use information with specific tool references.

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