Marketstack MCP Server

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

With no annotations provided, the description carries full burden for behavioral disclosure. It states the tool 'looks up information,' implying a read-only operation, but doesn't mention pagination behavior, rate limits, authentication needs, or what specific information is returned (e.g., timezone names, offsets, regions). The description is too vague about the tool's actual behavior.

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, clear sentence that efficiently communicates the core purpose. It's appropriately sized for a simple lookup tool with well-documented parameters, though it could be slightly more informative about the scope of 'information' returned.

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 low complexity (2 optional parameters, no output schema, no annotations), the description is minimally adequate but leaves gaps. It doesn't explain what 'information' includes or the tool's role in the broader financial API context, making it incomplete for optimal agent understanding.

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 description coverage is 100%, with both parameters (limit and offset) well-documented in the schema itself. The description adds no additional parameter semantics beyond what's already in the schema, so it meets the baseline expectation without compensating for any gaps.

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 action ('look up information') and resource ('all supported timezones'), making the tool's purpose immediately understandable. However, it doesn't explicitly differentiate from sibling tools, which are all financial data tools (e.g., get_bond_info, list_currencies), so this appears to be a standalone timezone utility in a financial API context.

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 or in what context it's appropriate. It doesn't mention prerequisites, dependencies, or typical use cases, leaving the agent to infer usage from the tool name alone.

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