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SEC EDGAR MCP

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Rust
Remote

Beneficial Ownership (13D/13G)

sec_beneficial_ownership
Read-only

Find who owns more than 5% of a company by reading Schedules 13D and 13G filings: holders' names, voting and dispositive power, share counts, percent of class, and stated purpose.

Instructions

Who owns more than 5% of a company: Schedules 13D and 13G, read from the filings themselves. Pass the company's ticker or CIK for the holders that have reported on it, or a holder's CIK (from sec_lookup_cik with 'name') for the companies that holder has reported on. Returns filings newest first, each with every reporting person's name, type (investment adviser, individual, …), sole and shared voting and dispositive power, aggregate shares and percent of class. A 13G is the short form for passive and institutional holders: it says which rule it is filed under, and 'exit_five_percent_or_less' marks a holder dropping to 5% or less. A 13D is filed by holders who may seek to influence control, and carries 'purpose' (Item 4: plans for the company, such as board seats or a sale) and 'source_of_funds' (Item 3). A 13G holder switching to a 13D is a signal worth noting. Amendments (/A) are included, since they are how holders report changes, so the newest filing per holder is their current position. Joint filers in one filing usually report the same shares: do not add their counts together. Filings before 18 December 2024 are HTML or text, listed with 'structured': false and a URL for sec_filing_text. Reads 5 filings by default and at most 10 per call; pass 'next_offset' back as 'offset' for older ones.

Input Schema

NameRequiredDescriptionDefault
limitNoNumber of filings to read (default 5, max 10). Each filing is one holder's (or one group's) report.
offsetNoNumber of most-recent matching filings to skip, for paging back (default 0). Pass the previous response's 'next_offset'.
tickerYesThe company whose 5%-plus holders you want: a ticker, e.g. AAPL, or a CIK. Or a holder's CIK (find it with sec_lookup_cik's 'name'), for the schedules that holder has filed on other companies.
form_typeNoOptional filter: '13D' (holders who may seek to influence control, with their stated purpose) or '13G' (passive and institutional holders). Omit for both. Amendments are always included: they are how a holder reports a change.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv0.10.0

TDQS

A4.6/5.0
Behavior4/5

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

Annotations only declare readOnly/openWorld, so the description carries real weight and adds substance: newest-first ordering, amendments always included, the 5/10 read cap, 'structured': false plus a URL for legacy filings, and the crucial joint-filer warning not to sum counts across reporting persons. It does not discuss rate limits or what happens when a holder has no filings, which keeps it below a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Information is front-loaded — the what, then the two input modes, then return shape, then interpretation caveats — and nearly every sentence carries distinct value. It is long and a few clauses (limit/offset restatement, 'a signal worth noting') are expendable given the schema already documents paging.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description fully covers the return shape: each reporting person's name, type, sole/shared voting and dispositive power, aggregate shares, percent of class, plus purpose/source_of_funds for 13Ds and the structured/URL pair for old filings. Combined with the joint-filer caution, an agent has everything needed to call and interpret results correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3; the description still adds meaning by explaining that 'ticker' doubles as a holder CIK and what each form_type value implies behaviorally (13D = may seek control with stated purpose; 13G = passive/institutional; omit for both). Pagination guidance largely restates schema text, limiting the upside.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Who owns more than 5% of a company: Schedules 13D and 13G') and pins scope to filings-based ownership rather than aggregated data. An agent can distinguish it from sec_institutional_holdings (13F) and sec_insider_transactions (Form 4) 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.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states both usage modes — company ticker/CIK for holders, holder CIK (via sec_lookup_cik's 'name') for the companies that holder reported on — plus when to use the form_type filter and how to page with 'next_offset'. It also routes pre-18-Dec-2024 HTML filings to sec_filing_text, naming the sibling alternative directly.

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

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