fetch

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

With no annotations, the description carries full behavioral disclosure. It explains point-in-time semantics, how as_of drops non-public rows, includes restatements, and how quarter selects a reporting period. The field-form catalog also sets expectations about what can be fetched. This is rich, non-obvious behavior clearly explained.

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 efficiently organized: a one-line purpose, a list of field forms with examples, and two key parameter explanations. Every sentence adds value, and the line breaks make it scannable. Despite length, there is no fluff.

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?

Complex tool with 8 parameters, no annotations, and an output schema. The description covers field forms, point-in-time behavior, and reporting period selection. It omits explicit guidance on date range parameters (start/end) and limit, but those are relatively intuitive. It comes close to complete but has minor gaps.

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 0%, so the description must compensate. It thoroughly explains the critical `field` parameter with many examples and covers `as_of` and `quarter` semantically. However, it does not describe `start`, `end`, `limit`, or `form`, leaving some ambiguity for a full parameter set. Still, the most important and confusing parameters are well handled.

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 opens with 'Fetch any field from any source, as point-in-time rows,' using a specific verb and resource type. It clearly distinguishes from siblings: 'discover' is for field discovery, while this is the actual fetching tool. The broad but explicit scope makes the purpose unmistakable.

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?

It explicitly says 'Run discover first if unsure' and explains when as_of and quarter matter. While it doesn't enumerate alternatives like events or backtest, the field-form examples and point-in-time semantics give clear context for when this tool is appropriate. It lacks an explicit 'when not to use' but the guidance is strong.

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