PayFast MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states this is an update operation but doesn't mention critical behavioral aspects like whether it requires specific permissions, if changes are reversible, potential rate limits, or what happens to unspecified parameters. For a mutation tool with zero annotation coverage, this leaves significant gaps in understanding its 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, efficient sentence that clearly states the tool's purpose without unnecessary words. It's appropriately sized and front-loaded, with every word contributing directly to understanding what the tool does.

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?

For a mutation tool with 6 parameters, no annotations, and no output schema, the description is incomplete. It doesn't address behavioral aspects, error conditions, return values, or how this tool relates to sibling subscription tools. The high schema coverage helps with parameters, but other contextual elements are missing.

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%, so the schema already documents all 6 parameters thoroughly. The description adds minimal value by listing which parameters can be updated (amount, cycles, frequency, run date), but doesn't provide additional semantic context beyond what's in the schema descriptions. This meets the baseline for high schema coverage.

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 ('Update') and resource ('a PayFast subscription's parameters'), specifying the exact fields that can be modified (amount, cycles, frequency, or run date). However, it doesn't explicitly differentiate this tool from sibling subscription tools like subscription.adhoc or subscription.pause, which would require a more specific distinction.

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 like subscription.adhoc or subscription.cancel. It lacks context about prerequisites (e.g., needing an active subscription) or exclusions (e.g., not for paused subscriptions), offering only a basic functional statement without usage context.

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