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 communicates that this is a destructive operation (implied by 'Delete' and 'Security cleanup'), specifies prerequisites and next steps, and clarifies that serviceId is optional for shared variables. However, it lacks details on error conditions, confirmation prompts, or irreversible effects, leaving some behavioral gaps.

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 efficient and easy to parse for an AI agent.

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 (destructive operation with 4 parameters) and lack of annotations or output schema, the description does a strong job covering usage context, prerequisites, and related tools. However, it doesn't explain return values or error behaviors, which would be helpful for a deletion tool. It's largely complete but has minor gaps in output expectations.

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 adds minimal value beyond the schema, only implying that environmentId is 'usually obtained from service_list' and noting serviceId's optionality for shared variables. This meets the baseline for high schema coverage but 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 specific action ('Delete a variable for a service in a specific environment'), identifies the resource (variable), and distinguishes it from siblings like variable_list, variable_set, and variable_bulk_set by focusing on single-variable deletion. It goes beyond just restating the name to explain the operation's scope.

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 (removing unused configuration, security cleanup) and exclusions (temporary disabling, bulk removal). It also lists prerequisites (service_list), next steps (deployment_trigger, service_restart), and related tools (variable_list, variable_set), offering comprehensive context for 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.