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

Annotations provide only readOnlyHint, and the description fills the gap extensively: the exact return shape ({cik, fundName, filingDate, periodOfReport, totalHoldings, totalValue, holdings}), row-level fields, the CUSIP licence restriction, 'do NOT sum across types' guidance, ~45-day EDGAR delay, and a concurrency limit. This is far beyond what annotations convey.

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 what the tool returns, then input forms, then payload shape and caveats; nearly every clause carries distinct operational information. It is dense and clause-heavy in places, but for a tool with no output schema that density is largely earned.

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?

No output schema exists, so the description must explain return values — and it does, enumerating the envelope and row fields, noting what is stripped (cusip) and what is absent (ticker). Combined with the resolution and concurrency notes, an agent has everything needed to call and interpret it correctly.

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 100%, so the baseline is 3, but the description adds real semantics: that resolution is recorded in `resolved_from`, that ambiguous names are refused with candidates rather than guessed, and that there is NO ticker field with `title_of_class` acting as the share-class discriminator. That reinforces the fund parameter's resolution contract beyond the schema text.

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 — the largest positions one institutional filer holds in its latest SEC 13F-HR, plus quarter-over-quarter changes. It is distinguishable from siblings like get_institutional_holders, get_institutional_consensus, and ol_13f_filer_analytics without opening any 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?

Clear context for use: one filer, latest 13F filing, with QoQ change framing, plus operational guidance ('Heavy operation, max 2 concurrent') and the input-resolution contract that governs correct invocation. It stops short of explicitly naming an alternative tool or a when-not-to-use condition in the description text (the ol_13f_filer_search fallback appears only in the schema).

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