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

Annotations already declare readOnlyHint and non-destructive behavior, so the description's job is lighter. The description adds meaningful behavioral context by stating it returns static reference data, listing the semantic pieces returned, and clarifying that no birth data is involved.

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 two tight sentences, front-loaded with the purpose and content expectations. The final sentence about no birth data is a useful discriminator, not filler.

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 lookup endpoint, this is largely complete: it names the input (id), describes the output contents, and signals the static nature. With no output schema present, a bit more detail about return shape could be helpful, but the description gives enough orientation for an agent to call it safely.

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?

The input schema already covers all parameters at 100% with detailed descriptions, enums, defaults, and examples. The tool description adds little to parameter semantics beyond framing the endpoint as a static center lookup, which is the expected baseline.

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 uses a specific verb and resource ('Look up ... static reference data for one of the nine Human Design centers by its id'), clearly listing what the data contains. It also distinguishes itself from the sibling computing endpoints by emphasizing 'no birth data required'.

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 makes the usage context clear: this is for static reference data without a birth chart. While it does not explicitly name alternatives like post_human_design_centers or post_human_design_bodygraph, the phrase 'pure reference endpoint with no birth data required' gives the agent strong situational guidance.

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