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

With no annotations, the description carries the full burden and does disclose meaningful traits: the result is version-dependent (the supported set can grow), it should be cached rather than re-fetched, and the return shape (languages[] with name/version/harvester) is spelled out. It does not state read-only semantics or any rate/permission expectations, but for a zero-parameter lookup that gap is minor.

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?

Three sentences, front-loaded with what is returned, followed by the integration rationale and the caching exclusion. The trailing "Returns languages[]..." sentence is redundant with the opening line but earns its place by enumerating entry fields compactly.

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?

No output schema exists, so the description must describe the response — and it does, down to the per-entry keys. For a zero-parameter, read-only lookup, an agent has everything needed to call it correctly and cache the result.

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 no parameters, so the baseline is 4 and there is no parameter meaning to add. The description instead documents the returned entry fields, which is value beyond the empty schema rather than a substitute for missing parameter docs.

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 ("Returns the current source-language list with harvester metadata") and immediately differentiates itself from the sibling generate_wiki by framing itself as a lookup that replaces hardcoding. An agent can locate this tool's role without opening any schema.

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?

Provides an explicit WHEN NOT TO USE block: do not call on every generate_wiki invocation, cache instead. It also names the alternative behavior it replaces (hardcoding language names) and the failure mode that motivates it, leaving nothing to inference.

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