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

Annotations already declare readOnly, idempotent, and non-destructive; the description adds valuable context such as default ordering ('newest first'), the pagination paywall ('Page 2+ requires FolioFact Pro'), and the universe of stocks ('all held stocks'). These go beyond the structured annotations to inform the agent of constraints.

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 two sentences, front-loads the primary purpose, and includes only high-value constraints (newest first, Pro requirement, filterability). Every phrase earns its place with no fluff or repetition.

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?

Given the tool's moderate complexity (6 optional parameters), strong annotations, and an existing output schema, the description covers the core semantics, scope, ordering, filtering, and a key limitation (Pro paywall). The output schema handles return value details, so the description is sufficient for an agent to select and invoke this tool 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. The description reinforces that the tool is filterable by transaction type and owner, which maps to parameters, and its pagination note aligns with the 'page' parameter already explained in the schema. However, it adds no new parameter-level detail beyond what the schema provides.

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 states a specific resource ('Form 4/5 insider transactions') and action/scope ('across all held stocks, newest first'), which clearly distinguishes it from sibling tools like fund_holdings or get_stock. It also mentions filterability, making the tool's function 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 clear context for when to use the tool (viewing recent insider transactions for held stocks) and implicitly excludes other uses by naming its specific scope. It does not explicitly name alternatives or when-not-to-use, but the domain is sufficiently distinct from siblings.

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