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

Annotations already declare readOnlyHint=false, destructiveHint=true and idempotentHint=false, so the mutation and safety profile is covered. The description adds one genuinely useful behavioral fact – 'Ongoing storage charges may apply' – but says nothing about reversibility (can it be unlocked?), the effect on the backup's lifecycle, or why a hint named 'destructive' applies to what reads as a protective action.

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 sentences, front-loaded with the effect and followed by the cost caveat; every word earns its place with no filler. It is arguably too terse for a 9-parameter destructive tool, but judged purely on conciseness it is efficient.

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?

No output schema exists, so explaining return values is unnecessary, but for a destructive, non-idempotent mutation with 9 parameters at 0% coverage the description leaves too much unstated: no parameter guidance, no confirmation that locking is (ir)reversible, and no scoping of the storage-charge warning.

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 9 parameters, so the description carries the full explanatory burden and provides none of it. The two required IDs (volumeInstanceId, volumeInstanceBackupId) are inferable from their names, but the seven beon_*/approval_id context parameters are completely undocumented in both schema and description.

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 gives a specific effect on a specific resource: preventing a volume backup from expiring, which is the semantic meaning of 'lock'. It is clear, but it never names the sibling tools it differs from (railway_delete_volume_backup, railway_restore_volume_backup, railway_list_volume_backups), so an agent must infer the distinction from the name alone.

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?

Usage is only implied: you lock a backup when you want to retain it past its expiry window. There is no explicit when-to-use, no when-not-to-use, and no mention of the alternative operations (restore, delete, create) that an agent would weigh against locking.

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