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

With annotations present the bar is lower, and the description goes beyond them by disclosing cost ($0.01 per call), the payment rail (USDC on Solana via x402), and the concrete challenge-and-retry protocol including the _meta["x402/payment"] key. That is exactly the kind of prerequisite/operational context annotations cannot express; only the response shape is left uncovered.

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?

Purpose is front-loaded in the first clause, followed by the payment mechanics and the HTTP equivalent, which are both actionable. The payment sentence is dense but every clause carries operational information; nothing is redundant.

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 tool with no output schema, the description covers purpose, cost, payment flow, and an alternate transport. The one gap is that it never says what a response looks like (record fields, ordering, volume/caps), which matters for a paid call with no declared output schema.

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 the single 'since' parameter is fully documented in the schema, including the strict-greater-than semantics. The description only restates 'since a timestamp' and adds no syntax or edge-case detail beyond the schema, so baseline 3 applies.

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 names a specific verb and resource ('atlas records added or changed since a timestamp') and enumerates the change classes it covers (terms changes, sunsets, status changes). This clearly distinguishes it from siblings like atlas_record (single-record lookup) without the agent needing to open 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?

The change-feed framing implies the polling/refresh use case, but there is no explicit when-to-use versus when-not guidance and no named alternative (e.g., use atlas_record for a single record, atlas_route for lookups). Usage is inferable but not stated.

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