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

With no annotations, the description carries the full transparency burden. It discloses the paid nature ($0.03 via x402), the lack of a row cap or time window, and the exact fields returned. It does not describe auth/failure behavior, but for a read-only historical query it gives enough context for an agent to gauge cost and scope.

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?

Approximately 55 words, every sentence earns its place: cost, scope, output fields, use cases, negative guidance, and input semantics are all included without repetition. It is slightly dense as one block, but nothing is extraneous.

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 two-parameter, no-output-schema, no-annotation tool, this description reasonably covers the output projection, cost, coverage, and the key `since` parameter. It misses explaining `payment_header` and does not describe response format details, but for the complexity level, it is sufficient.

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 0%, so the description must compensate. It explains the `since` parameter as a unix timestamp with 'omit it for everything we have', which is useful, but it never mentions the `payment_header` parameter, which is especially relevant for a paid tool. Half of the inputs are undocumented.

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 the resource (COMPLETE observed price-change history for every tracked LLM) and the action (audit, feed cost model). It differentiates from the sibling tool anansi_price_changes_recent by explicitly stating this is the full-archive version, not the recent snapshot.

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 explicit when-to-use guidance: auditing pricing behavior over the entire archive or feeding a cost model. Also provides a clear do-not-use directive for 'quick did anything change lately' checks and names the correct alternative tool. This is textbook disambiguation.

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