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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is known. The description adds genuinely new behavior: stored credentials are destroyed along with the account, while payments already sent remain readable in the business's own rail account. That retention detail is exactly the kind of post-destruction consequence an agent needs and is not in the annotations.

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 with the destructive action front-loaded, followed by the retention caveat. No filler. The one-word 'Keyed.' fragment is economical but its meaning is opaque without context.

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 two-parameter destructive tool with no output schema and annotations covering the safety profile, the description supplies the essential missing pieces: what else is destroyed (credentials) and what survives (settled payments). Minor gaps remain around immediacy/irreversibility of deletion, but nothing an agent needs in order to call it correctly is absent.

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%, with both access_key and connection_id documented, including the list_rail_accounts provenance hint. The description adds no further meaning about parameter format or constraints, so the baseline 3 applies.

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: 'Deletes a connected rail account and its stored credentials.' That is clearly distinct from the sibling connect_rail_account and list_rail_accounts. The leading 'Keyed.' is terse and its meaning (auth requirement) is not spelled out, which slightly blunts an otherwise clear statement.

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?

There is no explicit guidance on when to use this versus connect_rail_account or list_rail_accounts, nor any stated prerequisites or when-not-to-use condition. The only usage-adjacent information, that connection_id comes from list_rail_accounts, already appears in the schema.

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