einvoicing_timeline

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and a closed (openWorldHint=false) domain, so the safety profile is covered without the description's help. The description adds a genuinely useful behavioural note - that the data is 'current' but should be verified with the FTA/MoF, implying it may lag legislation - yet says nothing about caching, refresh cadence, or how the accreditation register is kept current.

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 opening sentence is well front-loaded, but the body enumerates specific Ministerial Decision numbers, exact appointment dates and go-live months - content that belongs to the return value and, with an output schema present, is redundant for tool selection. It is informative but padded rather than tight.

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 zero-parameter, read-only tool with full annotation coverage and an output schema, the description is more than sufficiently complete: it establishes subject, legal basis, data currency caveat and even the inclusion of the MoF ASP register. The only omission is any statement of how fresh the underlying data is.

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?

The tool takes no parameters (schema coverage 100%), so per the rubric the baseline is 4. There is no parameter-level information an agent could be missing, and the description correctly avoids inventing any.

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 first sentence gives a specific verb (Return) and three concrete resources (regime, rollout timeline, ASP deadlines), so the tool's scope is immediately legible. It does not, however, name or contrast itself with near-neighbours such as vat_filing_calendar or corporate_tax_estimate, so an agent must infer the boundary from domain knowledge alone.

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?

Usage is only implied: an agent can reasonably infer this is the tool for UAE e-invoicing phase-in questions, but the description never states when to reach for it, when not to, or which sibling covers adjacent tax-calendar questions. The closing 'Verify dates with the FTA/MoF' is a reliability caveat rather than routing guidance.

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