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

No annotations are provided, so the description carries the full burden. It discloses the cost ('Costs 1 api_sat per call'), the authentication flow ('Proof is verified by debit_or_deny before any cost is incurred'), and the output composition ('balance hero, metrics cards, health gauge, tranche table, and tool usage breakdown'). This goes beyond the schema, though it doesn't explicitly state whether the tool is read-only or describe failure modes.

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?

The description is two sentences, front-loaded with the main purpose, followed by output details and cost/verification. Each sentence earns its place with zero waste. It is concise and well-structured.

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?

The description is complete for a tool with an output schema and 3 parameters. It explains the return value (SVG with specific sections), the cost, the proof verification, and differentiates from a sibling tool. Given the output schema exists, the description need not elaborate on return value structure, and it doesn't omit critical context.

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%, so the baseline is 3. The description does not add any parameter-specific meaning; it only describes the overall output. Since the schema already documents each parameter thoroughly, no additional semantic value is provided, meriting a baseline score.

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 opens with a specific verb + resource: 'Generate a visual SVG infographic of your account statement.' It clearly distinguishes itself from the sibling brain_account_statement by stating that it 'Returns the same data as account_statement, rendered as a dark-themed SVG graphic,' making the purpose unambiguous.

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 implies when to use this tool by comparing it to account_statement: it provides the same data but in a visual SVG form. However, it doesn't explicitly say 'use account_statement for raw data' or list when-not conditions. The context is clear but not fully explicit, so a 4 is appropriate.

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