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

Annotations already declare readOnly/openWorld/idempotent/destructive, so the safety profile is covered. The description adds genuinely useful data-shape context beyond that: one file per half month with 'a'/'b' suffix meaning, and newest-first ordering.

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?

Three tight sentences, front-loaded with the core answer (what periods are published), then format, then usage. No filler.

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 no-arg, no-output-schema reference tool this is complete: it says what is returned, in what order, in what format, and why an agent would call it. Nothing needed to invoke it correctly is missing.

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?

Zero parameters, so baseline is 4. The description still adds value by explaining the 'a'/'b' half-month period convention, which is the vocabulary the downstream FTD tools expect for their period argument.

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 resource (SEC fails-to-deliver reporting periods), a precise scope (currently published) and ordering (newest first). The 'pick a valid period argument' framing cleanly separates it from the FTD query siblings (ftd_largest, ftd_security), which consume such a period.

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?

Gives two explicit use cases: choosing a valid period argument, and gauging data freshness. That is strong positive guidance, though it names no exclusions or the specific sibling tools that consume the period value.

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