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

Annotations cover the safety profile (readOnly, non-destructive, idempotent, closed-world), yet the description adds context they cannot: newest-first ordering, the archive-vs-live distinction, per-row billing with `limit` capping cost, and a warning that returns are untrusted user-generated content. These are material operational facts well beyond the structured hints.

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 verb, resource, and the critical archive-not-live caveat, then handles routing, return fields, billing, and the trust warning in compact order. Each sentence carries distinct information; nothing is padding.

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 compensates by enumerating returned fields (pk, id, code, taken_at, media_type, product_type, video_duration) and stating billing behavior. Combined with the ordering and trust notes, an agent has everything needed to call and interpret this tool.

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 both parameters are already documented (baseline 3). The description adds cost semantics to `limit` ('caps both rows and cost') and confirms `user_id` is the pk, giving value beyond the schema without fully reinventing it.

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?

Names a specific verb and resource ('Get Instagram stories stored in the DataLikers database for a user') and immediately scopes it as 'an archive of collected stories, not a live view of what is active now.' It also explicitly differentiates from siblings get_story_by_id and get_user_highlights, so an agent can select it without opening another 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?

State a direct usage condition ('Use it to review an account's story history') and name two alternatives with the conditions that select them ('get_story_by_id for one story's media URLs', 'get_user_highlights for pinned collections'). Routing is unambiguous.

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