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

Annotations already declare readOnly/idempotent/non-destructive; description adds dynamic behavior: fan-out to three sources, GDELT→GNews fallback on rate-limit/5xx, and USPTO soft-fail due to PatentsView sunset. Also explains return format (changes[] grouped by source, total_changes, citation URIs). No contradiction.

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?

Though single-paragraph, it's front-loaded with user-intent examples and packs essential details (federated sources, fallback behavior, input format, output shape, alternative tool) without fluff. Every sentence carries operational value.

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?

Covers input formats, sources, fallback, output structure, and usage boundary vs entity_profile. With no output schema, it adequately describes the return value, making it self-sufficient for an agent.

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 provides full descriptions for all three parameters (type enum, since format/examples, value ticker/CIK), so baseline 3 applies. Description adds broader context (e.g., that since drives the window across all sources) but doesn't add parameter-level syntax beyond schema.

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?

Description opens with natural-language query examples then clearly states it's a 'change feed for a company in the last N days/weeks/months in ONE parallel call', specifying sources (SEC EDGAR, GDELT/GNews, USPTO). It explicitly distinguishes from entity_profile ('Use entity_profile instead when you want the static profile').

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 via query examples and an explicit alternative: 'Use entity_profile instead when you want the static profile (filings + fundamentals + LEI + patents) regardless of window.' This covers when-not and alternative in one phrase.

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