Guard versions

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

Annotations already declare a safe, idempotent read, but the description goes beyond them by interpreting results: a null installed version means the library is absent and other tools would be 'guessing,' while a version mismatch between installed and docs_bundled_for is explicitly called normal. This is unusually rich disclosure of what the output means in practice.

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 key routing instruction is front-loaded in the first sentence and the field-by-field explanation follows logically. It runs long across several blocks and some return-field detail could be tightened, but every paragraph carries usable meaning rather than filler.

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 zero-argument introspection tool with an output schema and full annotation coverage, the description supplies everything an agent needs: when to call it, the returned fields, and how to interpret null versus mismatched versions. No gaps remain 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?

The tool takes zero parameters, which sets a baseline of 4. The description confirms 'It takes no arguments,' matching the empty schema, though there is nothing further to add.

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 verb and resource: reporting which Guard libraries this server can introspect and at which version. This is clearly distinct from siblings like validate_config, config_fields, and check_payload, which it names as dependent on the result.

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?

Explicitly says to 'Call this first, before trusting any answer about a version-specific feature,' and explains the downstream consequence: when a library is absent, validate_config, config_fields and check_payload cannot answer for it. When-to-use is stated directly rather than inferred.

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