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

Annotations only declare readOnlyHint=true, so the description carries the real behavioral burden and does so well: it discloses that a slow full-chart build yields a chart without customer and uninstalled-app accounts, flags partial: true, returns a hint, and advises a retry before treating an account as absent. That is exactly the kind of non-obvious runtime behavior annotations cannot express.

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 tight sentences, front-loaded with the resource definition, then the sibling routing, then the partial-result caveat. Every sentence adds distinct value with no filler.

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 read-only list tool with full schema coverage and no output schema, the description supplies everything an agent needs: what it returns, which sibling to prefer, and how to interpret and recover from a partial response. Nothing material is missing.

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 each of the five parameters (to, from, limit, query, cursor) already documented in the schema, including pagination and filter semantics. The description adds no parameter-level detail beyond what the schema provides, so the baseline of 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 the exact resource returned (the chart of accounts) and enumerates its constituent parts: own accounts, default accounts, app and customer accounts. It also explicitly carves out the sibling list_account_mappings, so an agent can distinguish the two without reading either 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?

Names the alternative tool and the condition that selects it ('For the category-to-account mapping use list_account_mappings'), and gives an explicit recovery instruction for the partial-result case ('call again in a minute before concluding an account is missing'). Both when-to-use and what-to-do-on-failure are covered.

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