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

Annotations provide readOnlyHint: true, and the description adds valuable behavioral context: the operation is scoped to the active Space and can be overridden with space_id. This goes beyond the annotation's simple safety hint and explains a session-dependent behavior.

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 description is two sentences, with the first sentence giving a clear, front-loaded purpose and the second adding scoping behavior. No unnecessary words or repetition.

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 simple read tool with readOnlyHint and no output schema, the description covers the core purpose and the space-scoping nuance. It omits details like not-found behavior or return format, but these are not critical given the tool's simplicity and the existing annotations.

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 schema already thoroughly describes space_id, but keyword_id has no description. The description adds minimal meaning by stating 'by id', which implies keyword_id is the identifier. With 50% schema coverage, the description does not fully compensate for the undocumented keyword_id parameter.

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 'Fetch one keyword by id' clearly identifies the action (fetch), the resource (one keyword), and the retrieval mechanism (by id), distinguishing it from list_keywords and other get_* tools. It also adds scoping context, making the purpose unambiguous.

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 states the tool is scoped to the active Space and explicitly directs users to set_active_space for switching or pass space_id to override per call. This provides clear context for use, though it does not explicitly contrast with list_keywords for fetching multiple keywords.

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