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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so '(read-only)' largely restates what the agent already knows. The description adds only the fact that filtering is possible; it says nothing about what a 'mount' entry contains, permission requirements, or any volume-scoped caveats, though the lower bar from annotations keeps this at a 3.

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?

Two short clauses, front-loaded with the action and resource, with zero filler. The terseness borders on telegraphic — the parenthetical and the trailing fragment read as notes rather than a complete sentence.

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?

An output schema exists, so return values need not be described. However, with four parameters and a required 'project' left undocumented, an agent still has to infer the key scoping argument from the name alone; the description is adequate but not complete for a filtered-list tool.

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 only 25% — just context_id is documented — so the description carries real weight. It does confirm that service and environment are optional filters, but leaves 'project' (the only required parameter) unexplained and says nothing about how project, environment and service compose.

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 ('List persistent volumes and mounts') plus a scope qualifier ('read-only'), so an agent knows exactly what this returns. It does not distinguish itself from siblings such as railway_services_list or railway_domains, so it stops short of a 5.

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 phrase 'Optional environment/service filters' implies the tool can be narrowed to a specific environment or service, which is implicit usage guidance. There is no statement of when to prefer this over other Railway inventory tools, nor any prerequisite or when-not-to-use note.

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