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

Annotations already mark this as readOnly/idempotent/non-destructive. The description adds non-annotation details: what the catalogue entry contains, the behavior when no argument is supplied, and the 404 cost consequence. 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?

The full JSON-RPC invocation for a sibling tool is bulky and front-loads information that is not about explain_document itself. The useful rule could be expressed in a few words; the example and catalogue explanation are concise but the opening block wastes space.

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 tool with one optional parameter and no output schema, the description covers the prerequisite workflow, conditional behavior, and return contents. It would be complete even without the output schema, though the meaning of '404 cost' is a bit terse.

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 already documents the optional name parameter. The description adds concrete meaning by showing that name='owners.json' returns that document's bot requester and that omitting the argument lists all 22 entries.

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 title and 'One catalogue entry' make clear the tool returns a per-document explanation (purpose, known clients, 404 cost, spec URL), which distinguishes it from listing/validation siblings. However, the opening JSON-RPC block to a sibling tool muddies the focus, so it stops short of a 5.

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?

The description implies the workflow: first call no_arguments_check_this_hosts_own_discovery_documents, then explain a specific document by name; omitting the name lists all 22 entries. It never explicitly states when to prefer this tool over its siblings or what conditions rule it out, so guidance is mostly inferred.

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