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

Annotations already indicate readOnlyHint and openWorldHint, so the bar is lower. The description adds valuable behavioral details beyond annotations: the cost ($0.05 per call) and the distinction between eventDate (when it happened) and filedAt (when disclosed). It also mentions that item codes are decoded, which clarifies output content. No contradictions with annotations.

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?

The description is two sentences, front-loaded with the core purpose, and efficiently packs in item code examples, date semantics, and pricing. Every sentence earns its place without redundancy.

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?

Given the tool's moderate complexity (4 params, no output schema), the description covers the essential aspects: what it does, key output fields (eventDate vs filedAt), item code filtering, and cost. It doesn't mention pagination, ordering, or output structure, but the schema and purpose are clear enough for an agent to infer typical usage. It is reasonably complete for an agent to select and invoke correctly.

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%, so the baseline is 3. The description adds a bit of extra context for the 'item' parameter by giving concrete examples of item codes (e.g., 5.02 for executive departures), which helps interpret the filter. However, it does not elaborate on other parameters beyond what the schema already provides.

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 clearly states the tool's function: parsing a company's 8-K filings into material events with decoded item codes, providing examples (5.02, 4.02, etc.). It distinguishes itself from siblings like filing_section or latest_filings by focusing on parsed events rather than raw filings or sections. The verb 'parsed' and the resource '8-K filings' are specific.

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 description implies usage for obtaining material events from 8-K filings, but it does not explicitly mention when to use this over alternatives like filing_section or recent_filings. It does provide cost information, which is relevant for usage decisions. However, no explicit when-not or alternative tool references are given.

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