upsert_account_balance_history

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

The description adds significant behavioral traits beyond the idempotentHint annotation: all-or-nothing atomicity ('if any entry fails validation, none are applied'), the past-month restriction, and the response shape ('only the entries submitted, not the account's full history'). These provide the agent with essential expectations for failure and return behavior.

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 concise sentences front-load the primary purpose then add key constraints (past month, atomicity, response scope). Every sentence is necessary, no filler words, and the structure is easy to scan. This is an exemplary model of concise tool documentation.

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 write operation with an array of nested objects and no output schema, the description covers critical context: what can be written, the current-month prohibition, all-or-nothing failure mode, and what the response contains. Combined with the fully descriptive schema and idempotent annotation, an agent has all necessary information to call this tool correctly.

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?

The input schema has 100% parameter description coverage, including nested fields like month, balance, symbol, etc. The description does not add parameter-level details beyond the schema; it repeats 'single account' which is already implied by account_id. Since the schema fully covers semantics, the baseline 3 is appropriate.

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 clearly states 'Create or update monthly balance history entries for a single account' - a specific verb-resource pair with scope (single account). It distinguishes from sibling balance-history tools by the upsert verb and explicit single-account focus, making its purpose unmistakable.

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 description gives clear operational context: it is for a single account, monthly entries, past months only, and all-or-nothing. However, it does not explicitly state when to prefer this tool over upsert_crypto_synced_balance_history or unlike get/delete tools. The schema's account_type description notes the crypto_synced alternative, but the description itself stops short of explicit alternatives.

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