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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so safety is covered structurally; the description adds genuinely non-obvious semantics — that an UNMEASURED axis is a published declared slot rather than an error or a zero, and that the output is never a certification. That absence-vs-failure distinction is the kind of context the schema cannot carry. It stops short of describing volatility, caching, or how the live board updates.

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?

Two sentences, front-loaded with identity and scope, then the interpretive caveat; nothing repeats the annotations verbatim. The field enumeration is dense and would scan better as a list, and 'first-class answer' is rhetorical rather than informative, but overall the length is proportionate to the tool.

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?

With zero parameters, an output schema, and full annotation coverage, the description supplies what the structured fields cannot: what the axis represents and how to read an empty result. The one missing piece is orientation among the many sibling axis readers and aggregators, which the description never addresses.

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?

Zero parameters, so the baseline is 4; the description also correctly reinforces that no argument is accepted, which matches additionalProperties:false and an empty properties object. No gap to compensate for.

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 names the specific resource (the watchdog-ingest axis of the GSPC board, with a base URL) and the row contents it surfaces (n, accuracy, interval, status, family, kind, URL, dates), which separates it from the other axis_* siblings by axis rather than by function. However, it never uses an operative verb — 'this tool IS the axis' describes identity, not an action, so an agent must infer that the tool reads/returns that axis row.

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?

'Takes no argument' sets the calling convention and the remark that an unmeasured axis is a valid answer implies when not to treat a result as failure. But it never routes between siblings: nothing says whether get_axis, measurement_index, or board_totals should be preferred in any situation, so usage is only implied.

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