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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is known. The description adds valuable behavioral context: the tool's dependency on DataCanvas, that it may not be listed without one, and that a canvas_id can expire (referenced in the schema). It goes beyond the annotations by explaining how the tool fits into a workflow and the consequences of missing prerequisites.

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 exactly two sentences, with the core purpose front-loaded and the conditional context provided in the second sentence. Every clause earns its place—no filler, no repetition of the tool name, and it efficiently packs purpose, usage, and environment constraints.

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?

Given that an output schema exists (so return values are specified separately) and annotations cover read-only and idempotent behavior, the description provides all remaining context an agent needs: the tool's role, required first-step nature, prerequisite, and the fallback behavior if the prerequisite isn't met. Nothing essential is missing for a correct 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 description coverage is 100%, and the schema itself already documents canvas_id with guidance on expiration and where to get a fresh one. The tool description does not add further parameter details beyond what the schema provides. Since the schema handles parameter semantics fully, a baseline of 3 is appropriate.

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 states a specific verb and resource: 'List tables and columns staged on a DataCanvas.' It explicitly names the data source (prior fx_get_timeseries call) and clearly differentiates its role from sibling tools like fx_dataframe_query (which is the next step) and the fx_get_rates/currency tools. This leaves no ambiguity about what this tool does.

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 gives explicit when-to-use guidance: 'Required first step before fx_dataframe_query — use it to discover table names and column schemas.' It also states a prerequisite (requires DataCanvas) and explains the alternative behavior if the prerequisite is missing ('fx_get_timeseries returns every range inline'). This fully orients an agent on when to call it versus relying on other tools.

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