get_invoice

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

The description discloses pricing tiers and the optional agent_id parameter's effect on cost, which is helpful. However, without annotations, it fails to specify whether the tool is read-only, if it creates state (e.g., a pending invoice), or any side effects like rate limits or authentication requirements.

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 brief at two sentences, conveying purpose and key pricing details efficiently. However, the tier list formatting is slightly dense and could be structured more clearly (e.g., as a table).

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 covers purpose and pricing but omits details about the output format, the relationship between karma and Giskard Marks, and any prerequisites (e.g., having a Giskard Marks account). The presence of an output schema mitigates the need for return value explanation, but behavioral context like potential side effects is 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 description explains the agent_id parameter's purpose (identity in Giskard Marks) and its behavioral impact on pricing. Given the schema has 0% coverage (no parameter descriptions), the description fully compensates, adding meaning beyond the schema's type and default.

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 retrieves a Lightning invoice for payment before searching, which is a specific verb and resource. It distinguishes itself from sibling get_arbitrum_invoice by implying a different blockchain (Lightning vs Arbitrum).

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 indicates when to use the tool ('before searching'), providing clear context for invocation. However, it lacks explicit guidance on when not to use it or alternatives, such as other payment methods or prerequisites like having a Giskard Marks account.

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