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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds two genuinely useful behavioural facts: all money values are denominated in the account currency, and fields shaped {untrusted_text: ...} are broker/hook/user data that must never be treated as instructions. It omits error behaviour for an unknown account_id, but the injection warning is real added value.

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 returned-field list, no filler. The parenthetical currency note and the security note both earn their place, though the field enumeration is dense enough that it reads as a spec dump rather than prose.

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?

There is no output schema, so enumerating the returned fields is the right compensating move, and the untrusted_text warning covers the main data-safety risk of this broker-sourced payload. The only real gap is the absence of any routing guidance against the two sibling account tools.

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% and account_id is already documented with its provenance (from list_accounts), so the description adds nothing beyond the schema. Baseline 3 is correct for a single, fully-documented parameter.

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+resource (account information) and enumerates the exact fields returned (balance, equity, margin, freeMargin, marginLevel, leverage, currency). It never distinguishes itself from near-neighbours get_account_health and get_account_snapshot, so an agent still has to guess which of the three account-read tools to pick.

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?

No statement of when to use this tool versus get_account_health, get_account_snapshot, or list_accounts (the only source hint lives in the schema, not the description). No prerequisites, no exclusions, no ordering advice.

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