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

Goes well beyond the readOnlyHint annotation: it discloses the hard LIMIT of 20 most recent rows, that `days` is a NO-OP, 4/A dedup behavior, isDerivative caveats, Plus-tier requirement, SEC EDGAR source with ~2-day filing deadline, and that caveats live in the response's tool_notes. This is rich operational context an agent needs.

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 the critical '20 MOST RECENT TRANSACTION ROWS ONLY' constraint in caps. Dense and information-rich, but the field-by-field enumeration of the response is long for a description; every clause is useful though, so no real waste.

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 fully describes the return shape ({ticker, transactions}), each row field, and how totals should be computed. Combined with the sibling routing and tier/caveat notes, an agent has everything needed to call and interpret it 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% so the baseline is 3, but the description adds meaning beyond the schema by warning that the `days` parameter is currently a NO-OP — which directly overrides the schema's own 'Number of days of history (default 365)' claim. It doesn't add syntax for `ticker`, keeping it from a 5.

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+resource ('Recent Form 4 insider transactions for one ticker') and immediately scopes it against siblings, explicitly naming ol_insider_recent_buys, ol_insider_cluster_scan, and get_activist_stakes as the tools for adjacent use cases. An agent can distinguish this from the other insider tools 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?

Provides explicit routing: 'Market-wide buys: ol_insider_recent_buys; clusters: ol_insider_cluster_scan; >5% stakes: get_activist_stakes', plus an instruction to filter on transType yourself and to exclude issuerSelfFiled rows from totals. When-to-use alternatives and in-tool handling rules are both present.

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