Upload a photo for a post

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

Description reveals the three-step upload process and the output format, adding value beyond annotations. Annotations already indicate non-read-only and non-idempotent, and the description complements them without contradiction.

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?

Three short sentences, each serving a distinct purpose: purpose, input/output, and parameter clarification. No redundant information.

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?

Tool has moderate complexity due to multi-step upload and output schema. Description covers input types, return format, and intended usage context. It does not detail error handling or step specifics, but this is acceptable given the output schema exists.

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 covers 100% of parameters. Description adds crucial nuance for group_id (positive, without minus sign) that prevents misuse, and confirms image supports both URL and local path. This goes beyond the schema's basic descriptions.

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?

Description clearly states the tool uploads a photo for attaching to a post, using specific verbs and resources. It distinguishes itself from sibling tools like vk_photos_get by specifying the upload purpose and output format.

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?

Description gives explicit context: the returned attachment string should be passed to vk_wall_post or vk_wall_edit. It also clarifies the group_id format. However, it does not mention when not to use this tool or suggest alternatives.

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