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

With no annotations, the description carries the full burden and does meaningful work: it discloses the cost ('1 api_sat per call') and the payment gate ('Proof is verified by debit_or_deny before any cost is incurred'), plus the visual components produced. It does not cover failure/refund behavior, but cost and verification are the operationally important traits here.

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?

Front-loaded with the purpose, then supporting detail on what is rendered and what it costs. Every sentence contributes; sizing is appropriate for the tool's complexity, with only mild redundancy in enumerating the visual components.

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?

An output schema exists, so the description needn't explain return values, and it correctly focuses on cost, verification, and the visual nature of the output. Combined with 100% schema coverage, the definition gives an agent everything needed to call it 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?

Schema description coverage is 100%, so all three parameters (days, npub, dpop_token) are already documented in the schema. 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 a specific verb and resource ('Generate a visual SVG infographic of your account statement') and explicitly names the sibling beesknees_account_statement as the source of the same data, so the agent can distinguish the visual variant from the raw-data one without opening 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 (account_statement) and its differentiator ('rendered as a dark-themed SVG graphic'), which tells the agent to pick this one when a visual is wanted. It stops short of an explicit 'use this when / don't use this when' rule, but the routing signal is clear.

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