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

With no annotations, the description carries the full burden. It usefully discloses that the window is bounded by a 'latest data date' (implying data is not real-time) and that only one SSIC filter is allowed, but it says nothing about ordering, pagination, or what a result contains.

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?

A single tight sentence with the recency constraint front-loaded and no filler. Slightly compressed to the point of leaving gaps, but structurally sound.

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 3-param read tool with no annotations and no output schema, the description covers the two most important concepts (time window, SSIC filter) but omits the limit/pagination parameter and any hint of result shape, leaving meaningful gaps.

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 0% and the description only addresses two of three params: 'last N days' maps to days and 'one SSIC code' maps to ssic, but neither format nor default/range is given. The limit parameter is completely undocumented in both schema and description.

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?

Specific verb (list) plus resource (companies registered in Singapore) with a clear recency scope, which implicitly separates it from search_companies and lookup_uen. However, it never names or contrasts with those siblings, so it stops short of a 5.

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?

No statement of when to pick this over search_companies or lookup_uen; an agent must infer that this is the 'recent registrations' tool. The 'optionally for one SSIC code' clause hints at a filter but is not usage guidance.

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