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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses a hidden write: 'if the Place ID is one SkimGuard has never seen, it is added to SkimGuard's own public location registry.' It also clarifies that this write is only to SkimGuard data and is read-only from the caller's perspective, aligning with the annotations rather than contradicting them.

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 description is moderately long but all sentences contribute: purpose, return values, use case, special cases, side effect, and read-only reconciliation. It is organized efficiently with no redundant filler.

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?

The description covers what the tool returns, when to use it, the not-publicly-tracked outcome, private residence exclusion, and the side-effect behavior. Given there is no output schema and the annotations are present, this is a complete picture for an agent to select and invoke the 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%: all three parameters (placeId, days, response_format) have descriptions in the schema. The description adds little beyond restating 'by its Google Place ID' and implying 'how recently' maps to days. Thus it meets the baseline for schema-heavy documentation but doesn't exceed it.

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 opens with 'Look up SkimGuard card-skimmer scan status for a location by its Google Place ID' – a specific verb (look up), resource (status), and identifier (Place ID). It also summarizes the return values, distinguishing it from sibling tools like skimguard_search_locations or skimguard_location_devices.

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?

The line 'Use this to answer "is this gas station / ATM / store safe to use my card at?"' gives a clear use case. However, it does not explicitly mention when not to use it or alternative tools for cases like missing Place ID, so it falls short of full 5.

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