Fetch a single tag by id. Resolves to null with a NOT_FOUND error when no tag has that id, and with an UNAUTHORIZED error when the tag belongs to an organization the caller cannot read. Both are reported in the errors array. This API is an early preview and can change without a deprecation period.

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true, establishing a safe read operation. The description adds valuable context beyond these: it specifies error behaviors (NOT_FOUND, UNAUTHORIZED with error codes), notes the API is an early preview subject to change, and clarifies that provider errors are failures even with HTTP 200. This is good transparency for a read tool 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 description is reasonably concise and front-loads the core purpose and error behaviors. The appended sentence about pagination and provider errors is somewhat abrupt but relevant. The structure is logical: purpose, error handling, preview status, then operational notes. No major verbosity.

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?

Given the complexity (5 parameters, nested objects like payload), annotations covering safety, and 100% schema coverage, the description is complete enough. It covers error handling and preview status, which are critical for error-prone calls. The only gap is lack of guidance on tool selection relative to siblings, but for a single-resource fetch with comprehensive schema, this is acceptable.

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%, so the schema already fully documents all parameters including id, fields, account, payload, and payload_file. The description adds little parameter semantics beyond noting 'Use upstream fields to bound data,' which hints at the 'fields' parameter but doesn't provide additional syntax or constraints beyond the schema. Baseline 3 is appropriate when schema is comprehensive.

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 clearly states a specific verb+resource ('Fetch a single tag by id'), which is unambiguous. However, with the exception of the sibling 'get_tags_v2' which is plural, there's no explicit differentiation from other 'get_' tools, though the resource 'tag' is specific enough. The core purpose is clear.

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 provides no guidance on when to use this tool versus alternatives like get_tags_v2 for listing tags or get_post for other resources. It mentions using upstream fields to bound data, but that's a parameter usage hint, not tool selection guidance. No conditions for use or exclusions are stated.

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