graph_render

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

Annotations only cover readOnlyHint and openWorldHint, and the description goes beyond them by disclosing the return type and its intended consumer (base64 data URI consumable by multimodal models). It does not mention the security disclaimer preamble or raw_json pitfalls, though those live in the schema field description.

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, zero filler: purpose first, output format second, prerequisite last. Every sentence contributes actionable 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?

For a read-only render tool with a full output schema and 100%-covered parameters, the description supplies the essentials: what is produced, in what format, and how to get the required ID. Error/limit behavior (size bounds, PolicyError on raw_json) is covered in the schema rather than here.

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%, so width, height, period, server, graphid, and raw_json are already fully documented in the schema, and the description adds no formatting or syntax detail beyond the graph_get hint for graphid. Baseline 3 is appropriate when the schema does the heavy lifting.

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 and resource ('Render a Zabbix graph as a PNG image') and names the exact output artifact, which separates it cleanly from the many *_get siblings. It also routes to graph_get for ID discovery, reinforcing its distinct role.

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?

Gives an explicit prerequisite/alternative: 'Use graph_get to find graph IDs first,' which tells the agent how to obtain the required graphid. It does not state when *not* to render (e.g. prefer history_get/trend_get for raw numbers), so it falls short of full when/when-not guidance.

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