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

With readOnlyHint/openWorldHint already declared, the description still adds substantial behavioral context: provenance (the service's own daily reads), the effective coverage window, the clamping behavior on since, the scope limit (election-level facts only), and the fact that pages can disappear, become unreadable, or be restored. These are non-obvious traits an agent could not infer from the schema or 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?

Front-loads the core question in the first sentence and keeps the whole thing to a handful of dense clauses with no filler. The middle sentence is an unusually packed enumeration, and the trailing 'Check the official page' caveat is stylistically clipped, but every element carries information.

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 structure need not be described, and the annotations cover the safety profile. What remains — data source, history start, window clamping, and the limitation to election-level facts — is exactly the context an agent needs before invoking this change-tracking tool.

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 parameter names, formats, bounds and the change_type enum are already fully documented and the baseline is 3. The description adds meaning the schema does not: that an earlier-than-30-days since is silently clamped rather than rejected. It adds nothing further about limit or prefecture semantics.

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 operation (reporting what changed) on a specific resource (Japanese prefectural election schedule pages) with an explicit time scope, and enumerates the six change categories it can report. That enumeration makes it clearly distinguishable in practice from elections_upcoming, but no sibling tool is named as an alternative or contrast, which is the only thing separating this from 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?

Gives real usage context: history starts at tracking_since, the free window is the last 30 days, earlier since values are clamped, and it points to history_window for details. It also warns to verify against the official page. It stops short of stating when to prefer this over elections_upcoming or catalog, so no exclusions or alternatives are named.

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