MerchantHQ Card Acquirer Index

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

Since no annotations are provided, the description bears the full burden of behavioral disclosure. It explicitly states the tool is 'Read-only,' a critical safety trait. Furthermore, it specifies the nature of the returned data ('factual terms... plus regulatory identifiers').

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 highly efficient, consolidating the resource definition, filtering methods, return data characteristics, and safety constraint into a single, coherent paragraph without any wasted language.

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?

The description provides all necessary information for an agent to successfully invoke the tool and understand the scope of the results, even though no output schema is present. The behavioral details and return data types compensate completely for the lack of formal output definition.

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?

While the schema covers the input parameters (tier, query, channel), the description adds significant semantic value by detailing the *content* of the results, listing specific data points such as 'headline rate, settlement timing, contract length, channels.' This context enhances understanding beyond the input schema.

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 purpose: to 'Search UK card-payment acquirers and processors in the MerchantHQ Card Acquirer Index.' It is highly specific regarding the resource and geographical scope.

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?

Since there are no sibling tools, there is no need to differentiate usage. However, it only describes the filtering capabilities (query, tier, channel) without explicitly stating prerequisites or complex usage scenarios. It is adequate given the lack of alternatives.

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