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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open world), and the description adds materially beyond them: truncation is flagged, the list may legitimately be empty, empty answers are still charged, the first cached result is free, otherwise $0.003 USDC via x402. Event date vs filing date separation, amendment labeling, and EDGAR links are disclosed output behavior.

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?

Front-loaded with the core action and window, then detail; every sentence carries information. The first sentence is dense but readable, and the pricing/legal notes are compressed into a short final clause. Minor density cost, not waste.

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 fully specifies the return shape (item codes plus titles, separate event and filing dates, amendment labels, EDGAR links, truncated flag, possible empty list) as well as the payment path. An agent has everything needed to call and interpret it.

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% for both parameters, so the schema already documents ticker format and the x402 payment-retry flow. The description adds the payment economics and the 'US-listed company' constraint but no additional parameter syntax or semantics beyond what the schema states; 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 precise verb+resource+scope: reads up to 20 Form 8-K material events a US-listed company filed in the last 90 days. The enumerated item codes (1.01, 1.05, 2.06, 3.01, 5.02) and the explicit exclusion of earnings-only filings make it unmistakable versus siblings like otto_equity_news or earnings tools.

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 context is implied by the scope (material corporate events, 90-day window, 20-item cap) and it explicitly excludes earnings-only filings, which helps routing. However, it names no alternative sibling tool and gives no explicit when-not-to-use guidance beyond that single exclusion.

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