generate_svg_sparkline

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

With no annotations, the description carries the behavioral disclosure burden. It adds useful traits: 'lightweight', 'zero-dependency', and the cost note '(0.01 USDC on Base L2)', which signals a paid operation. It does not explicitly state that invoking the tool charges the fee, but the parenthetical is a meaningful disclosure beyond the schema.

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 with no filler. The core purpose is front-loaded, and the cost note is the only additional sentence, which earns its place because it relates to a required payment behavior.

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 input schema's only required parameter is a generic 'payload' string with a circular description, and the tool description never explains how to structure the numeric series JSON. While the output type is hinted at as SVG, there is no output schema and no concrete payload contract, leaving an agent with insufficient information for confident invocation.

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 coverage is 100%, so the baseline is 3. The description adds that the payload relates to a numeric series, which provides a hint, but it does not specify the expected JSON structure, key names, or format. The expense signature parameter is already adequately described in the schema.

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 ('Generates') and a precise resource ('SVG inline sparkline charts'), with input sources ('from numeric series') and intended domain ('agent financial reporting'). The 'lightweight, zero-dependency' qualifiers help distinguish it from siblings like generate_placeholder_svg and generate_qr_code_svg.

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?

Provides a clear use context through 'from numeric series' and 'for agent financial reporting', which indicates when it is appropriate to use. It does not explicitly name alternatives or exclusions, but no sibling sparkline tool exists, so the context is sufficient.

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