reddit_by_id

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

Beyond the readOnly/openWorld annotations, the description discloses a non-obvious behavioral trait: the result is not always one-to-one with the request, and it explains the meta fields (listing_status, truncated, missing_fullnames) and which one to branch on. This is exactly the kind of partial-failure detail an agent cannot get from 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?

Front-loads the core behavior (bulk fetch in one call), then the usage cue, then the return shape and meta-branching, ending with a concrete example. Every sentence carries distinct information with no 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 still names the returned fields (title, author, score, comment count, permalink) and the meta envelope, and it flags the caveat that responses may be partial. Nothing an agent needs to call and interpret this correctly 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 already documents the t3_ format and the 100 cap, so the schema carries the load. The description's inline example is mildly reinforcing but adds no syntax or constraint beyond what the schema provides.

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+resource (bulk-fetch posts) with a clear scope constraint (by t3_ fullnames, up to 100) and explicitly contrasts it with a per-post request pattern. It is distinguishable from siblings like reddit_post or reddit_subreddit_posts because it is keyed on ids, not listings.

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?

Tells the agent to pass fullnames 'you already have from a search or listing to hydrate them', which gives clear context for when this tool applies. It implies the batching alternative to per-post calls but does not name a specific sibling (e.g. reddit_post) as the single-id fallback, so it stops short of explicit when-not guidance.

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