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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds significant behavioral context beyond annotations: the intent is read/discovery, it mentions pricing (paid read-premium), routing (estimate cost first, then paid tool if needed), and signer boundary (hosted reads never receive keypair bytes). This provides valuable transparency for execution.

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 front-loaded with purpose, followed by protocol context and usage guidance. It is well-structured but slightly redundant (pricing info appears in both description and input schema). Overall, it is concise and informative, earning a 4.

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 one-parameter readonly tool with output schema present, the description is complete. It explains what the tool returns, when to use it, and execution specifics (pricing, routing, signer boundary). No gaps remain.

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 a clear description for actionUrl: 'Solana Action URL (https endpoint implementing the Actions spec).' The tool description does not add further parameter details beyond what the schema already provides. Baseline 3 is appropriate since schema does the heavy lifting.

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 'Fetch metadata for a Solana Action (Blink) — returns title, description, available actions, and parameters.' The verb 'fetch' and resource 'metadata for a Solana Action (Blink)' are specific. It distinguishes from sibling tools like blinks_buildActionUrl (building URLs) and blinks_executeAction (execution), making the purpose unambiguous.

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 explicit use cases: 'Use for Solana Actions and Blinks metadata fetch, validation, and POST action preparation. Preview and validate actions before signing or submitting transactions through SAP transaction tools.' This guides when to use the tool, though it does not explicitly list when not to use or name alternative tools for other scenarios. However, the sibling list implies alternatives.

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