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

Beyond the annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=false), it discloses valuable behavioral facts: it 'does not send money, trade NFTs or request wallet secrets,' and it requires an already-authorised wallet transfer plus signed claim. The retry-key guidance reinforces the idempotency hint. It omits permission requirements and rate limits, but adds real context.

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, front-loaded with the core purpose before the workflow and the safety disclaimer. Every sentence contributes, though the middle sentence packs multiple actions and constraints together, slightly reducing scannability.

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 10-parameter mutation tool with no output schema and near-zero schema coverage, the description covers the flow, the safety boundary, and the verify outcome ('receive an access pass') reasonably well, but leaves most parameter-level detail and permission requirements unaddressed.

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 only 10% (just account_ref), so the description carries the burden for 10 parameters, yet it only gestures at concepts behind signature, transaction_hash, spending_authorized and checkout_key. It says nothing about action, method_id, package_id, accept_terms, or name, leaving most parameters unexplained in both schema and prose.

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 states a specific verb (purchase) and resource (prepaid ECLYPSE access) and clarifies the distinguishing scope: 'without registration or a human profile,' which sets it apart from sibling eclypse_register_agent. It also names the three sub-actions (create/read quote, verify transfer) that map to the action enum, so an agent can tell what it does without opening the schema.

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?

It gives clear operational context: the create/read-then-verify workflow is spelled out, and it explicitly instructs 'Use the same checkout key for retries.' It does not name alternative siblings (e.g. eclypse_register_agent or eclypse_create_invoice) or state exclusions, so it stops short of a full when/when-not routing guide.

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