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

The description goes well beyond the minimal annotations (readOnlyHint: false, openWorldHint: true) by disclosing the HTTP method, the uniform { ok, data, meta, error } response envelope, all supported authentication paths, where to get a key, and that failed calls cost no credits. This is valuable operational behavior not visible in the schema or 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 first sentence is front-loaded and substantive: call an engine action and receive a uniform envelope. The auth options are explained in one dense sentence, and the 'Failed calls cost no credits' line is useful. It is long, but the complexity of auth justifies the length.

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 generic engine-call proxy with no output schema, the description supplies the response envelope, parameter-discovery prerequisite, authentication mechanics, and cost behavior. Nothing an agent needs to safely invoke it 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%, so the schema already documents engine, action, and params. The description adds a pointer to get_engine_schema/get_action_schema for valid param names, but this mostly restates the guidance already present in the input schema. It does not add new parameter-level meaning beyond the schema.

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 target: 'Call a ReefAPI engine action — POST /<engine>/v1/<action>' and states the return envelope. It is clearly distinguishable from sibling metadata tools like get_engine_schema, get_action_schema, and search_engines because this is the execution tool.

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 gives concrete sequencing: 'Get param names from get_engine_schema first,' and the param schema repeats this with get_action_schema. It also explains which server and auth mode to use. It does not explicitly state when not to use call_engine, but the contrast with the schema-lookup siblings is clear.

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