ava_viz

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

Annotations only declare openWorldHint=false and destructiveHint=false; the description adds materially more, including that the absolute output path must be new and its parent directory must already exist, that rendering requires network for GPT-Vis, and that a generated HTML file does not prove visual rendering. It also warns that arbitrary query column names are not inferred and that labels/values/units should be previewed. It stops short of describing what the tool returns or how failures surface, keeping it at 4.

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 core action, then requirements, caveats, and routing in roughly priority order, with no filler sentences. It is dense to the point of reading as a run-on block of imperatives, but each sentence carries a distinct constraint.

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 tool spanning twenty-plus chart variants with no output schema and no parameter descriptions, the description covers the schema contract, filesystem preconditions, network dependency, data-fidelity limits, and the sibling alternative. What remains missing is per-chart-type field mapping for the less common types, which the schema's oneOf branches largely supply.

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 0% at the top level, so the description carries the burden and does: spec requires chartType and config, output must be an absolute new path with an existing parent. It also maps native data fields per chart type (category/value for column, time/value for line) and requires JSON numbers. The remaining chart types' field mappings are left to the schema's oneOf branches.

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: "Render verified query results as a GPT-Vis chart HTML." It immediately separates itself from the report path by naming ava_artifact with chartFields as the alternative, so an agent can route 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?

Explicit routing rules: use this for a requested standalone chart, use ava_artifact with chartFields for reports, and answer simple questions directly without a chart. Both the when and the when-not are stated, along with the named alternative.

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