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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds substantial context beyond them: exact redaction behavior for secrets and `senderSignature`, the fact that target secrets stay redacted, the guarantee that re-sending a target with its `id` preserves stored secrets, and specific error conditions. This is rich behavioral disclosure for a read operation.

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?

The purpose is front-loaded and the dense field enumeration is justified because there is no output schema. However, the single long sentence with nested parentheticals is harder to parse than a more structured presentation would be.

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 no output schema, the description carries the burden of explaining return shape, and it does so comprehensively: all returned fields, secret redaction semantics, and error cases are covered. Annotations already cover safety, so no critical information is missing for correct invocation.

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 mentions `lineKey` and `endpointId` only as identifiers and adds error behavior for their absence, but it does not add format or syntax detail beyond what the schema already provides.

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 specific verb and resource: 'Get one endpoint's full document by `lineKey` and `endpointId`.' This clearly distinguishes the tool from siblings like list_endpoints (plural), create/update/delete_endpoint (mutations), and get_line_draft (drafts), so an agent can identify it without inference.

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 states error conditions (missing arguments, nonexistent line/endpoint) and names update_endpoint's `patch` as the downstream editing path, giving clear context for a primary use case. It does not explicitly say when to prefer this over list_endpoints or other read tools, so the guidance is clear but lacks exclusions.

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