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

With no annotations, the description carries the full burden, and it delivers: discloses read-only nature, no cost, on-chain verification logic, and the fallback lookup behavior. It does not state failure semantics (error vs. boolean result) or return format, which is a minor gap for a verify tool given zero annotation coverage.

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?

Three sentences with zero waste: core verification logic front-loaded, then lookup methods, then a concise safety note. Every sentence earns its place and the most important information appears first.

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 tool with no annotations and no output schema, the description covers verification semantics and lookup well, but does not explain what the agent receives on success or failure, nor whether both parameters can be provided together. This is a meaningful gap for an MCP tool with no structured output contract.

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 coverage is 100% and both parameters are well documented in the schema, so the baseline is 3. The description adds the nuance that payment_ref 'always works' and clarifies the relationship between the two lookups, adding marginal value beyond the schema but not compensating for anything missing.

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?

States a specific verb (verify) and resource (AgentToll receipt against live Solana state), then defines what verification means concretely: PDA owner must be the AgentToll program and the stored digest must match. This gives an agent a precise mental model and implicitly differentiates from siblings get_receipt (fetch) and issue_receipt (create).

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?

Provides clear lookup guidance: primary key receipt_id, with payment_ref as the reliable fallback ('always works — the receipt lives on-chain'), reinforced by the schema's 'use this if receipt_id unknown.' However, it does not explicitly state when to choose verify_receipt over get_receipt, leaving the verify-vs-fetch decision to inference.

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