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

Annotations declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive; the description adds far more: the multi-source fan-out, sources_used/sources_failed semantics, patents API sunset soft-fail, GDELT→GNews fallback, and the explicit 'empty is real no-data, not a bug' guidance. This is exactly the behavioral context an agent needs and cannot infer from annotations alone.

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 dense but rambling, containing a garbled fragment ('Note: EDGAR submissions (FilingSummary) — that's expected;') that is confusing and breaks the flow. Several caveats about empty results are repeated across sentences, making the structure less crisp than it could be for such a long definition.

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 two parameters and no output schema, the description carries the burden of explaining return values, and it does so thoroughly: the exact fields returned, URI format for filings, sources_used/sources_failed distinction, per-source caveats, and fallback chains. The only notable gap is the unclear EDGAR submissions note, which leaves ambiguity about what 'expected' refers to.

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?

The schema already covers both parameters 100%, and the description adds meaningful clarification: type and value are interchangeable, value can be a ticker, zero-padded CIK, or company name, and name resolution occurs via SEC EDGAR. The description also explains what happens for unresolved private companies, extending parameter semantics beyond the raw 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?

The description is anchored by concrete user intents ('Tell me about X', 'research Acme', 'brief me on Tesla') and defines the tool as a 'full cross-source profile of a US public company in ONE parallel call'. It clearly names the operation and resource, and the 'ALWAYS PREFER' line distinguishes it from single-source SEC/XBRL/news lookups.

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 explicitly tells the agent to prefer this tool over chaining single-pack SEC/XBRL/news lookups when a holistic view is requested, which is a strong when-to-use signal. It also explains input acceptance and the private-company resolved:false behavior, but it does not explicitly name sibling tools like deep_research or compare_entities as alternatives one should consider instead.

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