Compare two addresses character by character

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

Annotations already declare readOnly, idempotent, non-destructive, and openWorldHint=false. The description adds real context beyond them: 'Runs locally' reinforces the no-network posture, and it discloses output behavior (reports every differing position, flags look-alikes sharing first/last characters).

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?

Three tight sentences, front-loaded with the threat ('Catch address poisoning') followed by the action and the local-execution note. No filler; every clause 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?

For a two-string, no-output-schema tool, the description covers when to use it, what it returns in prose (differing positions plus look-alike flag), and the local-execution constraint. Nothing an agent needs to call it correctly is missing.

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% with two clearly documented params ('actual' = address about to use, 'expected' = from trusted source). The description restates that ordering but adds no format, encoding, or validation detail beyond the schema, so the baseline 3 applies.

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 verb and resource ('compare the address you meant with the one you are about to send to') and frames the threat model ('catch address poisoning'). A comparison tool is inherently distinct from the sibling scan_address/scan_message single-artifact scanners, so an agent can pick it without opening the schema.

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 a clear trigger: before sending, compare the intended address from a trusted source against the destination. It implies the when-to-use well, but never names an alternative tool (e.g., scan_address) or an exclusion, so it stops short of explicit routing.

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