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

With no annotations, the description carries the full burden; it does disclose two useful traits, that the read is deterministic and drawn from the service's own stored snapshots rather than a live upstream feed. It omits error behavior for unknown codes, pagination/limit behavior, and freshness or staleness characteristics of the snapshots.

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?

Two short sentences, front-loaded with the core resource, with no filler. The second sentence is slightly redundant with 'stored snapshot history' but does add the determinism trait, so it still earns most of its place.

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?

There is no output schema and no annotations, so the description should say more about what a snapshot record contains and how results are ordered or bounded. 'Availability sampled since launch' hints at contents, but return shape and volume behavior remain unspecified.

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 both 'code' and 'limit' are already documented in the schema, and the description adds only the singular framing that history is per carpark code. The baseline of 3 applies when the schema does the heavy lifting.

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 gives a specific noun phrase ('Our stored snapshot history for one carpark code') and scopes it with 'availability sampled since launch', so the resource and its time window are unambiguous. It does not explicitly name the sibling get_carpark_availability or state the live-vs-stored distinction, so differentiation is inferred rather than stated.

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 guess this is for historical snapshots rather than current availability, but the description never says when to prefer it over get_carpark_availability or list_carparks. No exclusions, prerequisites, or routing guidance are given.

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