big-mcp-b3

fundamentus_ativo

Fetches fundamental data for a Brazilian stock ticker, such as P/L, P/VP, ROE, and margins, enabling informed investment decisions.

Instructions

Obtém fundamentos de uma ação (P/L, P/VP, ROE, margens, etc.) via fundamentus.com.br

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "ticker": "<ticker>"
    },
    "name": "fundamentus_ativo"
  }
}

Input Schema

Name	Required	Description	Default
`ticker`	Yes	Ticker da ação (ex: PETR4, VALE3, ITUB4)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 4, 2026

TDQS

B3.1/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states it's a web-scraping tool (via fundamentus.com.br) but doesn't disclose whether data is live or cached, potential rate limits, failure modes when the site is unreachable, or whether the tool handles format variations in ticker input (e.g., PETR4 vs PETR4.SA). For a scraping-based tool, these behavioral traits are significant gaps.

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?

The description is a single efficient sentence that conveys the purpose and source in ~15 words. No wasted words, appropriately front-loaded. It's slightly under-specified relative to the completeness needs, but for a single-line description it's appropriately concise.

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

Completeness2/5

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

This is a web-scraping tool with no annotations and no output schema. The description doesn't explain what the return data looks like, which fundamentals are included beyond the examples, whether data freshness varies, or error handling for invalid tickers. For a scraping tool reaching an external site, the description should disclose more about behavior and data structure.

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

Parameters3/5

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

Schema coverage is 100%, with the single ticker parameter having a clear description with examples (PETR4, VALE3, ITUB4). The description does not add parameter information beyond the schema, so the baseline of 3 is appropriate since the schema fully documents the parameter.

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

Purpose4/5

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

The description uses a specific verb 'Obtém' (obtains) with a clear resource 'fundamentos de uma ação' and lists concrete fields (P/L, P/VP, ROE, margens). It clearly states the data source (fundamentus.com.br). It doesn't explicitly distinguish from sibling tools like cotacao_ativo or historico_ativo, but the focus on fundamentals is reasonably distinct from those.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

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

The description implies usage through the fields listed (fundamentals for stocks), but provides no explicit when-to-use guidance or exclusions. Siblings like cotacao_ativo (quotes) and historico_ativo (history) suggest the context, but there's no explicit direction on when to choose this tool over comparisons, options, dividends, etc.

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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