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

Annotations already mark it read-only, idempotent, and non-destructive. The description adds behavioral detail beyond that: parallel probing of 19 prefix categories, flagging plaintext IMAP/POP3/LDAP without encrypted variants, and a caveat about negative results. No contradiction with 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?

Four sentences with no waste: core action, output behavior, open-world caveat, and explicit usage trigger. The purpose is front-loaded and every sentence earns 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?

Given full schema coverage, an output schema, and annotations covering safety and open-world semantics, the description covers purpose, outcome, a key interpretive caveat, and when to invoke it. Nothing essential is missing for an agent to use it correctly.

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 description coverage is 100% so the baseline is 3. The description stays at the tool level and does not restate parameter meanings; all parameter semantics are already covered by the schema. No additional value is added beyond the schema here.

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 action (map), resource (domain's DNS-visible service footprint), and method (probing 19 common SRV record prefixes). The outcome – returns discovered services and flags insecure advertisements – distinguishes it from sibling DNS checks without needing to open 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?

Provides an explicit 'Use when asked to map DNS-visible services or flag insecure service advertisements' trigger. It also gives a guardrail with the open-world caveat: a domain with no matches is not proof of no services, telling the agent how to interpret empty results.

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