mcp-agent-reliability

estimate_token_cost

Estimate token usage for tool definitions in the agent context window to decide on progressive loading.

Instructions

Roughly estimate how many tokens a list of tool definitions will consume in the agent context window. Helps decide whether to enable progressive loading.

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": {
      "tools": "<tools>"
    },
    "name": "estimate_token_cost"
  }
}

Input Schema

Name	Required	Description	Default
`tools`	Yes	List of tools with their name and description

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jul 31, 2026

TDQS

A3.7/5.0

Behavior3/5

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

No annotations are provided, so the description carries the burden of behavioral disclosure. It notes the estimate is 'rough,' setting expectations about accuracy, but does not disclose return format, potential side effects, or how the estimate is computed. For a non-destructive estimation tool, this is minimal but not misleading.

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

Conciseness5/5

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

The description is two sentences that are front-loaded and free of redundancy. The first sentence states the core function, the second adds the decision context. No filler or unnecessary detail.

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

Completeness3/5

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

The tool has a simple input schema and no output schema. The description covers purpose and use case but does not specify the return format (e.g., numeric value, range, aggregate) or whether the estimate is per-tool or total. This is a moderate gap, though acceptable for an estimation tool.

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?

The input schema already provides 100% coverage for the single 'tools' parameter, including nested object structure and descriptions. The tool description adds context about tool definitions and token consumption, but does not add significant detail beyond what the schema already specifies.

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?

The description clearly states the tool's action and resource: 'estimate how many tokens a list of tool definitions will consume in the agent context window.' It also provides context for its use case, distinguishing it from sibling tools like score_tool_description or reliability_report.

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 when deciding on progressive loading ('Helps decide whether to enable progressive loading'), but it does not explicitly state when not to use it or mention alternative tools. Guidance is implied rather than explicit.

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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