MCP Stock Market

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 the tool calculates total value but doesn't explain how (e.g., using real-time prices, cached data, or requiring external price lookups), what happens with invalid symbols, or if there are rate limits or authentication needs. For a calculation tool with zero annotation coverage, this leaves significant behavioral gaps.

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?

The description is a single, efficient sentence that directly states the tool's purpose without unnecessary words. It is front-loaded with the core action ('Calculate total value') and appropriately sized for its simple function, making it easy for an agent to parse quickly.

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?

Given the tool's complexity (a calculation requiring external data), lack of annotations, and no output schema, the description is incomplete. It doesn't address how the calculation is performed (e.g., integration with price data), error handling, or return format, leaving the agent with insufficient context for reliable use.

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?

The schema description coverage is 100%, with the 'holdings' parameter fully documented in the schema as an array of objects with 'symbol' and 'shares'. The description adds no additional parameter semantics beyond implying the tool uses these holdings to compute a total. Since the schema does the heavy lifting, the baseline score of 3 is appropriate, as the description doesn't enhance parameter understanding.

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?

The description clearly states the tool's purpose as 'Calculate total value of a portfolio given holdings', which specifies the verb ('calculate') and resource ('portfolio value'). It distinguishes from siblings like 'getStockPrice' or 'convertCurrency' by focusing on portfolio aggregation rather than individual stock data or currency conversion. However, it doesn't explicitly differentiate from potential portfolio-related tools not listed, keeping it at 4 instead of 5.

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?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites, such as needing current stock prices from other tools, or compare to siblings like 'getStockPrice' for individual values. Without any usage context or exclusions, the agent must infer based on tool names alone, which is insufficient for optimal selection.

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