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 effectively discloses that this is a mutation tool ('Update'), mentions prerequisites and next steps, and clarifies exclusions. However, it doesn't detail behavioral traits like required permissions, rate limits, or whether changes are reversible, which would be valuable 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 with clear sections (Best for, Not for, Prerequisites, Next steps, Related) and uses bullet points for readability. It's appropriately sized, but some sections (like 'Related') could be more concise or integrated into the 'Not for' guidance to reduce redundancy.

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 (10 parameters, mutation tool) and lack of annotations/output schema, the description does a good job covering purpose, usage, and exclusions. However, it could better address behavioral aspects like error handling or response format, which are important for a configuration update tool with many optional parameters.

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 parameters thoroughly. The description doesn't add any parameter-specific details beyond what the schema provides, such as explaining relationships between parameters or usage examples. This meets the baseline of 3 when schema coverage is high.

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 a specific verb ('Update') and resource ('service's configuration'), and it distinguishes from siblings by explicitly naming alternatives for excluded use cases (variable_set, service_restart, deployment_trigger). The title is null, but the description fully compensates.

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 on when to use ('Best for: Changing service settings, Updating resource limits, Modifying deployment configuration') and when not to use ('Not for: Updating environment variables, Restarting services, Triggering new deployments'), with named alternatives for each exclusion. It also lists prerequisites (service_list, service_info) and next steps (deployment_trigger).

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