Read one post

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds substantial behavioral nuance beyond that: it details exactly what is returned (tags with kinds and counts, media, dimensions, score, rating, uploader, comment count, source, and date) and clarifies that 'The link is read rather than followed.' This adds real value without contradicting any 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 a single, well-structured paragraph that front-loads the core purpose and then enumerates return fields. It is somewhat dense but every sentence contributes information (usage, identification methods, return contents). No filler or redundancy is present, though it could be trimmed slightly without losing essential detail.

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 read-only tool with an output schema, the description is nearly complete: it captures usage context, identification methods, and a full list of returned data. It does not address what happens if both parameters are supplied or neither, but given that both are optional and the schema defines them, this is a minor gap. The presence of an output schema further reduces the need to explain return formats.

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?

Both parameters are thoroughly described in the schema (100% coverage): id is 'The post's numeric id, as a search returns it' and url includes an example and notes that the link is read rather than followed. The description reiterates these but introduces no new semantic detail. With full schema coverage, the baseline of 3 is appropriate; the description does not elevate it further.

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 opens with a specific verb and resource: 'Read one rule34.xxx post'. It further specifies the identification method ('by its id or by a link to its page'), which clearly distinguishes it from its siblings (search_posts and find_tags). The tool's unique role—retrieving full details for a single post—is unambiguous.

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 explicitly states when to use this tool: 'Use this after a search, whose rows show only the first few tags of each post.' This provides clear context and implicitly differentiates it from searching or tag-finding. It does not explicitly name alternatives or exclusion conditions, but the usage direction is strong enough for an agent to select correctly.

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