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

Annotations already declare readOnlyHint=true and openWorldHint=true, but the description adds the non-obvious side-effect profile: nothing is persisted and the target host is never contacted. That is exactly the extra context annotations cannot express. It stops short of noting rate limits or result freshness beyond 'latest'.

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?

A single front-loaded sentence with a tight parenthetical for the behavioral caveats. No preamble, no restated title, nothing that could be cut.

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 one-parameter read tool this is nearly sufficient, but with no output schema the description should indicate what a 'latest certificate' response contains (issuer, validity window, SANs) or its empty/failure shape. As written the agent knows what goes in but not what comes back.

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?

One parameter at 0% schema coverage, so the description must carry the load. Saying 'hostname' does convey that the input is a bare host name rather than a URL or full certificate body, but format rules (no scheme, no port, no path) and the 253-character bound are left entirely to the schema.

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 resource and source: the latest certificate for a hostname, pulled from public CT logs. It is clear in isolation but never distinguishes itself from the sibling lookup_cert (or lookup_domain), so an agent cannot tell which one to pick from this text alone.

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?

No when-to-use, when-not-to-use, or alternative routing is given. With lookup_cert and lookup_domain sitting right beside it in the tool list, the absence of any disambiguation rule leaves the selection ambiguous.

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