Comments on a Reddit post

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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces this with 'Read-only, 0 credits'. It adds valuable behavioral detail beyond the annotations: the credit cost (0), the connection requirement, and the presence of a fullname field in each row for use with reply_to_reddit_comment. It does not mention rate limits, error behaviors, or pagination, but for a read-only list tool the added context is solid.

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 moderately sized but front-loaded with the core action and fields in the first sentence. The second sentence provides useful context about the value of the thread (questions, objections, customer wording) and ties it to sibling tools. The third sentence explains the output's utility for replying, and the final sentence states read-only, credits, and connectivity. Every sentence earns its place; it's slightly longer than necessary but not bloated.

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 list tool with no output schema, the description covers the key return fields (author, text, score, own-reply flag, timestamp) and the integration point (fullname for reply_to_reddit_comment). It states prerequisites and credit cost. It does not explain sort options or limit behavior, but those are already in the schema. Given the simplicity of the tool and the richness of the schema, the description is complete enough for an agent to invoke it correctly.

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?

Input schema coverage is 100% with each parameter already described (sort enum, limit range, postId types). The description adds no additional parameter-level meaning; it only implies that postId can be a permalink or fullname via the schema, but the description doesn't elaborate. The mention of 'fullname' is about the output rows, not the input parameters. Thus the description does not enhance parameter understanding beyond what the schema already provides, aligning with the baseline 3.

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 the verb 'Read' with a specific resource: 'the comments under one of the connected account’s Reddit posts'. It lists the exact fields returned (author, text, score, whether it's the poster's own reply, and when), which makes the purpose unambiguous. It also explicitly distinguishes itself from siblings by naming list_meta_comments and list_youtube_comments as the counterparts on other channels, so an agent can easily tell it apart.

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 clear context for when to use this tool: it positions it as the Reddit source for 'the same raw material for ad copy' that the Meta and YouTube comment tools provide. It also includes a prerequisite ('Needs Reddit connected') and hints at the downstream use case via 'the fullname to pass to reply_to_reddit_comment'. However, it does not explicitly state when NOT to use it or mention alternative tools beyond the two named siblings, so it stops short of a full exclusion list.

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