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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description goes well beyond that by defining each lifecycle state's meaning, noting that 'content holds the sections delivered so far' during a background write, and disclosing that a job object with progress and credits charged appears only when a background job wrote it — real behavioral context an agent could not get from the structured fields.

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?

Front-loads the action and scope, then spends its second sentence on the status-check caveat that matters most for correct invocation. The parenthetical status glossary is dense and slightly listy, but each element maps to a distinct return field that would otherwise be undocumented given there is no output schema.

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?

With no output schema, the description carries the return-shape burden and does so thoroughly — naming the fields an agent will act on and interpreting the lifecycle states. The single input parameter is fully covered by the schema, so nothing material is missing.

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 description coverage is 100% and the single parameter's origin ('from list_generations or generate_content') is already stated in the schema description. The prose adds no syntax, format, or constraint detail beyond that, so the baseline 3 for full schema coverage is appropriate.

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 ('Fetch one past generation in full') and enumerates exactly what is returned: lifecycle status, content, outline, brief, word count, word_count_target, voice-match score, and a job object. This clearly separates it from siblings like list_generations and list_draft_versions, which are collection-oriented.

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 warns to 'Check status before acting on the content' and explains the operative conditions ('outline' has no draft to polish or edit; 'generating' is unfinished), which effectively routes the agent to polish/edit only for complete drafts. It does not, however, name a sibling tool to use instead or contrast itself with list_generations for discovery.

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