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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful scope information (which signal types are included), but says nothing about result volume, ordering, or whether results are grouped per company — the main behavioral unknowns for a multi-signal aggregator.

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?

Front-loaded with the core action and scope in the first clause, followed by a compact enumeration of signal types. The signal list is long but each item is genuinely informative about coverage; only minor tightening possible.

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 read-only, single-optional-parameter tool whose only parameter is fully documented, the description is nearly sufficient. The remaining gap is that it doesn't say whether output is grouped per company or how much data to expect, but that is modest given no output schema exists.

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% and the single `days` parameter already documents its default and bounds. The description adds no additional meaning about the window semantics, so baseline 3 applies.

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?

States a specific verb and resource ('get what changed at the companies on the user's watchlist') and enumerates the covered signal types, so the agent knows exactly what surface this covers. The watchlist scoping also distinguishes it from the many search_* siblings that query signal types across all companies.

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 phrase 'the user's watchlist' combined with 'covers the same companies and signals as the 9am watchlist email' gives a clear selection context: use this for watchlist-scoped monitoring. It stops short of naming an explicit alternative (e.g., search_sec_filings when you want a specific signal across all companies), so no exclusion guidance.

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