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

Annotations already convey non-readOnly, openWorld, non-idempotent, non-destructive. The description adds genuinely new context on top: that creation may kick off a deployment and incur charges, and that a BEON PASS approval is mandatory. It doesn't explain approval expiry or what the service state looks like after the call, so it stops short of 5.

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?

Three short sentences, front-loaded with the action, then the risk, then the gate. Nothing is redundant and no sentence can be dropped without losing signal.

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 10-parameter mutation with no output schema, the description covers purpose, cost exposure, and the approval prerequisite well. It does not cover the BEON PASS workflow that most of the parameters imply, nor the relationship among the required projectId and name, so an agent still cannot confidently fill the 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 0% across 10 parameters, so the description carries the full burden. It hints at source.repo/source.image ('from a repository or public container image') and at approval_id ('Requires exact user approval'), but the seven other beon_* parameters (context, resume/release ids, environment enum, connection id) and the projectId/name distinction are entirely undocumented.

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?

States a specific verb and resource ('Create a Railway service') plus the two source types (repository or public container image), which the sibling names alone don't reveal. It is distinguishable from railway_create_project and railway_create_environment by the 'service' noun, though it never explicitly contrasts them.

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?

It discloses two important conditions ('May trigger deployment and charges', 'Requires exact user approval in BEON PASS'), which is real guidance about consequences. However, it gives no when-to-use vs when-not framing relative to siblings such as railway_deploy_service or railway_configure_service, leaving the routing decision to inference.

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