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

Annotations only declare readOnlyHint=true, so the description carries the weight and does so richly: keyless callers get stored rows and never trigger the EDGAR refresh, users must read stale/stale_basis, and caveats ride in tool_notes. It also disambiguates is_activist (a form-type label, not a judgement) and reports_zero (an exit OR reporting realignment).

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 purpose and facts dense with no filler, but the single long em-dash-chained sentence makes the freshness and reports_zero caveats harder to scan than they need to be. Nothing is wasted, though structure could be slightly lighter.

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?

No output schema exists, yet the description enumerates the return shape ({ticker, count, filings}) and the row fields, and covers freshness, ordering, and interpretation caveats. For a two-parameter read tool this is complete enough to call correctly.

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 coverage is 100% (baseline 3), but the description still adds the newest-first ordering, which is required to interpret what limit actually truncates, plus a restatement of the default 50 and hard cap 200. It is a modest but real addition beyond the 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?

States a specific verb and resource (Schedule 13D/13G >5% beneficial-owner filings for a ticker) and immediately distinguishes it from the sibling concept of quarterly 13F filings. An agent can tell exactly what this returns without opening any schema.

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?

Names alternatives explicitly with the condition that selects them: cross-check get_institutional_holders before reading reports_zero as a sale, and it cites get_institutional_consensus as a complement. It also frames the tool's niche (event-driven stake-building) against 13F, so the agent knows when to reach for it.

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