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

Annotations already cover safety (readOnlyHint, openWorldHint), yet the description adds genuinely new operational facts: a $0.01 USDC per-successful-call charge on Base, the wallet prerequisite, and the behavior that boolean/unknown EOL values are left unchanged. It still omits failure/payment-failure handling, so not a 5.

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 dense sentences with no filler: purpose first, then the asOf/computation behavior, then cost and auth. Information is front-loaded and each clause earns its place.

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?

With no output schema, the description still conveys the shape of the result (lifecycle dates, source flags, daysToEol), the cost, and the auth prerequisite, and annotations cover the read-only/open-world profile. Nothing essential to calling it correctly 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?

Schema description coverage is 100%, so all three parameters are already documented, and the description's notes on asOf driving daysToEol and on 'exact' release identifiers largely restate the schema. Baseline 3 is appropriate.

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 ('look up') plus a well-defined resource ('one exact endoflife.date product/release and project lifecycle dates and source flags'), which no sibling tool covers, so it is easily distinguishable. The phrase 'source flags' is slightly opaque, keeping it just below the top mark.

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?

Usage is implied by the resource (fetch lifecycle data for a product/release) and the prerequisite 'Requires an x402-capable wallet client' is stated, which is useful context. However, it never says when to prefer this over related lookups or what to do if no wallet is available, so guidance is only partial.

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