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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds meaningful semantics: that the output is aggregated facet counts scoped by the search filters. It does not discuss result caps or that facet values come from the filtered universe, but the annotation bar is met with useful added context.

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, front-loaded with the tool's purpose and followed by the sibling routing. No filler; every clause adds information.

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?

An output schema exists, so return values need not be described, and the facet/aggregation behavior plus sibling routing are covered. The only minor gap is not stating which filter dimensions are actually aggregateable versus pass-through, but overall complete for a facet tool.

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%, so the schema already documents page, sort, cusip, facet, page_size, issuer_name and manager_cik. The description only restates that facet selects manager or issuer, which the schema already specifies. Baseline 3 is appropriate 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+resource (return facet-count data for SEC institutional-position records) and immediately names what it is not (the search tool that returns position records). The agent can distinguish this facet-aggregation tool from datasets_sec_institutional_positions_search 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?

Explicitly routes the agent: use this for facet counts, use datasets_sec_institutional_positions_search for position records. It also clarifies that the same cusip/manager/issuer filters apply, so the agent knows the input conventions carry over from search.

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