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

Annotations already declare readOnly=true and idempotent=true, so the bar is lower, but the description goes further: it explains the parallel fan-out to multiple APIs, the GDELT→GNews fallback on rate-limit/5xx, and the PatentsView API sunset causing a soft-fail. These are rich behavioral details that help an agent anticipate outcomes without invoking the tool.

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 longer than average, but every sentence carries useful information: source details, fallback logic, date formats, output shape, and an explicit alternative tool. The opening examples and the closing entity_profile call-out earn their place; it could be tightened but is not padded.

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?

This is a complex tool with multiple data sources, fallback behavior, and no output schema. The description covers input formats, source-specific caveats (including a sunsetting API), return structure (changes[] grouped by source, total_changes, citation URIs), and when to use a sibling tool. It is fully actionable 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?

Input schema covers 100% of parameters, so baseline is 3, but the description adds value by giving concrete examples for `since` (ISO "2026-04-01", relative "7d", "30d", "3m", "1y") and recommending "30d" or "1m" for typical monitoring. It also clarifies `value` as ticker or zero-padded CIK, which supplements the schema's generic descriptions.

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 opens with example queries then states 'change feed for a company in the last N days/weeks/months in ONE parallel call', clearly identifying the verb and resource. It lists the data sources (SEC EDGAR, GDELT→GNews, USPTO) and explicitly contrasts with entity_profile, distinguishing it from a sibling tool.

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?

It provides concrete user intents ("What's new with X" / "latest on Y") and explicitly says 'Use entity_profile instead when you want the static profile... regardless of window.' It also explains the GDELT→GNews fallback and when each source is used, giving an agent clear selection criteria and expectations.

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