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

readOnlyHint=true already tells the agent this is a safe non-mutating read, so the bar is lower. The description adds that balances are returned, which partially compensates for the absent output schema, but it says nothing about not-found/error behavior or data freshness.

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, zero filler, with the operation front-loaded and the endpoint appended as a compact reference. Every clause earns its place.

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 one-parameter read tool with annotations covering the safety profile and no output schema, the description supplies the essentials: what is fetched, that balances come back, and the underlying endpoint. Only minor gaps remain, such as error behavior for an unknown id.

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?

There is one parameter with 100% schema description coverage ('Ledger account id.'), so the schema carries the full parameter burden. The description repeats 'by id' without adding format, source, or lookup guidance beyond what the schema already states.

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 ('Get a single ledger account by id') and the word 'single' implicitly separates it from the sibling list_ledger_accounts. It adds that balances are included, which is useful scope detail. It stops short of naming the list sibling explicitly, so it is clear but not maximally differentiating.

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 'by id' implies this is for fetching one known account rather than enumerating accounts, which is enough to infer usage. However, there is no explicit when-to-use statement, no exclusion, and no pointer to modern_treasury_list_ledger_accounts for discovery-style lookups.

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