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

Beyond the readOnlyHint and idempotentHint annotations, the description discloses multi-source fan-out (SEC EDGAR, GDELT→GNews, USPTO), fallback logic (GDELT preferred, GNews on rate-limit/5xx), and a soft-fail due to PatentsView API sunset. It also states the return structure (changes[], total_changes, citation URIs), which is valuable behavioral context.

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 leads with high-signal trigger phrases, then the core purpose, followed by source details and output format. Despite its length, every sentence adds value (fallbacks, soft-fail, return shape, sibling differentiation). No filler or 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?

For a multi-source, complex tool with no output schema, the description provides complete invocation context: it explains sources, fallback behavior, time-window formats, output structure, and the alternative tool. An agent would have enough information to select and correctly invoke this tool.

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 100%, with each parameter already well-documented (type enum, since format with examples, value ticker/CIK). The description largely repeats this information (e.g., 'since accepts ISO date or relative shorthand') and adds minimal new meaning beyond a minor recommendation already present in the schema. Thus 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?

The description clearly identifies the tool as a 'change feed for a company in the last N days/weeks/months' with concrete trigger phrases like 'What's new with X'. It explicitly distinguishes itself from sibling entity_profile ('Use entity_profile instead when you want the static profile'), making the tool's purpose and scope unmistakable.

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 provides explicit when-to-use guidance via trigger phrases, and directly names an alternative: 'Use entity_profile instead when you want the static profile (filings + fundamentals + LEI + patents) regardless of window.' It also clarifies fallback behavior and source specifics, giving the agent clear conditions for selection.

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