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

With readOnlyHint, idempotentHint, and destructiveHint already declaring the safety profile, the description still adds behavioral value: 'Newest first' ordering, the definition of 'since' as the recorded date in Sydney, and the caveat that a value can be recorded long after it began to apply. It does not mention pagination beyond the limit param, but the added ordering and time-semantics context go meaningfully beyond the annotations.

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 core purpose and ordering are front-loaded in the first two sentences, with the date semantics following. Most sentences earn their place, though the effective_from/applies-from discussion drifts into return-value territory and is slightly redundant for selecting and invoking the tool.

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?

An output schema exists, so return values need not be documented; the description nonetheless explains effective_from, which overlaps with the output contract. For a read-only list tool with a well-documented schema and annotations, the definition is essentially complete for correct invocation, with only minor redundancy.

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 real meaning the schema lacks: 'since' is clarified as the recorded date in Sydney (timezone absent from the schema), and the recorded_on vs applies-from distinction disambiguates the filter. The mention of effective_from is an output field rather than a parameter, which is a slight mismatch but it aids interpretation.

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 verb and resource ('lists what this site has changed in its published Australian retirement figures') with an explicit scope ('since a date') and enumerates the change kinds returned. This clearly separates it from siblings like get_figure and search_figures, which fetch current values rather than a change log.

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 implied by the change-log framing and the 'since a date' constraint, but there is no explicit when-to-use vs when-to-use-alternatives guidance, no exclusions, and no routing to siblings. Minimum viable rather than helpful.

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