Railway MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries full burden. It discloses this is a destructive operation ('Delete'), implies security implications ('Security cleanup'), and mentions prerequisites and dependencies. However, it doesn't specify authentication requirements, rate limits, or error behaviors, leaving some gaps 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?

Well-structured with clear sections (API action, Best for, Not for, Prerequisites, Next steps, Related), using symbols for visual clarity. Every sentence earns its place—no redundant information, and it's front-loaded with the core purpose.

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 destructive mutation tool with no annotations and no output schema, the description does well by covering purpose, usage guidelines, and dependencies. However, it lacks details on return values or error handling, which would be helpful given the tool's complexity. Sibling context is adequately addressed through related tools.

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 parameters are well-documented in the schema. The description adds minimal value beyond the schema—it mentions 'service in a specific environment' and 'shared variable' context, but doesn't provide additional syntax or format details. Baseline 3 is appropriate given 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 ('Delete a variable for a service in a specific environment'), identifies the resource (variable), and distinguishes it from siblings like variable_set (create/update) and variable_list (read). The title is null, so the description fully carries the purpose definition.

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?

Explicitly provides 'Best for' scenarios (removing unused configuration, security cleanup, configuration management) and 'Not for' cases (temporary variable disabling, bulk variable removal), plus prerequisites (service_list) and next steps (deployment_trigger, service_restart). This gives clear guidance on when to use this tool versus alternatives like variable_bulk_set for bulk operations.

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