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

Annotations already declare create semantics (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the description is free to add what they don't say: the auth refusal, template content differences (STARTER with no transactions vs SAMPLE with demo transactions), and the setup/template exclusivity rule. Note the mild tension between idempotentHint=false and the requestId idempotent-retry option, though the latter is clearly opt-in so this is not a contradiction.

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 sentences, front-loaded with the required parameter and ownership scope, then the optional surface and the refusal rule. The nested parenthetical for template is dense but each clause carries a distinct constraint rather than repeating the schema.

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 create tool with annotations, an output schema, and 67% parameter coverage, this covers what the schema can't: default template behavior, exclusive setup option, credential restriction, and retry semantics. Only the setup preset vocabulary (personal@1, blank@1, etc.) and capability values are left entirely to 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?

With 67% schema coverage, the schema already explains name, private, template, and description. The description still adds real meaning by stating the mutual-exclusion rule between setup and template and by framing requestId as idempotent-retry support, which the schema leaves as a bare string. The nested setup object's preset/capability semantics remain 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?

A specific verb plus resource ("Create a ledger") with explicit ownership scope ("owned by the authenticated user"). The description covers the full creation surface (name, template, setup, requestId) and the refusal condition, so an agent can distinguish it from listLedgers, updateLedger, and deleteLedger without opening the schema.

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?

Gives concrete calling conditions: name is required, setup is mutually exclusive with template, and the call is refused for ledger-pinned credentials. It does not point at alternatives for previewing a setup (previewLedgerSetup exists as a sibling), so the routing guidance is incomplete.

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