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

Goes well beyond the readOnlyHint/openWorldHint annotations: discloses the data source, that the record's refresh timestamp matters, and crucially that seen=false with known=false is not proof the port is closed. It also states the pricing model and that failed calls are not charged, which is behaviorally significant for a paid x402 tool.

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?

Four sentences, front-loaded with the core action and immediately followed by the important interpretation caveat. The pricing sentence is longer than needed but is legitimately useful for a metered 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, yet the description still explains the key return semantics (seen/known and refresh timing), covers data provenance, false-negative interpretation, and cost. Nothing material is missing for correct invocation and interpretation.

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% and the single parameter is documented, so the baseline is met by the schema. The description reinforces that the input is an IPv4 address and frames the parameter in terms of what the returned record means, adding modest value.

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: checks Shodan's passive scan records for TCP port 445 (SMB) on an IPv4 address. The parenthetical '(not a live test)' distinguishes it from active scanners like security_open_port_scanner and the SMB focus separates it from security_rdp_exposure_check and security_shodan_host_summary.

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?

Explains the operating mode (passive Shodan records, not live probing) and what a negative result means, which is exactly the context an agent needs to interpret results correctly. It does not explicitly name an alternative tool to use when a live check is required, which keeps it short of a 5.

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