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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses the exact execution behavior: one TLS handshake from a specific server, a 5 s timeout, and a full status envelope with ok, not_applicable, timeout, and error variants. It even tells the agent how to interpret non-success results, which is valuable operational context.

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?

Every sentence earns its place: the purpose and fields come first, then the use case and non-goals, then the concrete protocol behavior, then the return contract and interpretation guidance. It is compact while carrying a lot of decision-relevant 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?

With one parameter and no output schema, the description fully compensates by documenting the output shape, all possible status variants, the timeout behavior, and how the agent should interpret not_applicable vs error. Nothing essential for selecting or invoking this tool 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 description coverage is 100%, and the schema already explains that domain must be a public domain name and rejects IPs, ports, paths, and protocol prefixes. The description adds the port-443 context but does not materially enrich the parameter meaning beyond the schema, so the baseline of 3 is appropriate.

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 a precise verb and resource: 'Read the TLS certificate a domain presents on port 443', then enumerates the specific certificate fields returned. It also distinguishes itself from sibling tools by explicitly stating it does not test cipher suites or protocol versions.

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?

It clearly says when to use the tool ('Use to check expiry or a name mismatch') and states an important non-goal ('It does not test cipher suites or protocol versions'). It does not, however, name a specific sibling tool as the alternative for cipher/protocol testing, so the guidance stops short of fully explicit rerouting.

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