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

Annotations already declare readOnlyHint and idempotentHint, so safety is covered. The description adds genuinely new behavioral context beyond them: the dependency on a prior spill operation and an environment-variable availability gate. It stops short of describing behavior when the canvas is missing or expired, which is the only real gap.

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?

Three short sentences, zero redundancy. Purpose comes first, the routing instruction second, and the availability constraint last — exactly the right order for an agent deciding whether to call it.

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?

With an output schema present, the return shape needn't be described, and the single parameter is fully covered by the schema. The description supplies the two things structured fields cannot: the upstream dependency and the environment gate.

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?

Only one parameter, and the schema already documents canvas_id at 100% coverage including its 10-character pattern and provenance. The description reinforces that the canvas comes from a prior oecd_query_dataset spill but adds no format or constraint detail beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 ('List tables and columns staged on a DataCanvas') plus the origin of that data ('a prior oecd_query_dataset spill'). It is clearly distinguishable from the sibling oecd_dataframe_query, which it positions as the consumer of this discovery step.

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 sequencing instruction: 'Call this before oecd_dataframe_query to discover exact table and column names for SQL.' It also names a hard gating condition ('Only available when CANVAS_PROVIDER_TYPE=duckdb is set'), so an agent knows both when to call it and when it cannot be called at all.

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