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

With no annotations, the description carries the full burden. It discloses the temporal behavior—that the bar eventually closes and the signal disappears—and clarifies that the tool only reports time rather than grading it. It does not cover permissions, side effects, or output format, but for an informational tool the key behavior is present.

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 purpose is front-loaded in the first sentence, with a compact example that clarifies edge behavior. The three-sentence structure is efficient, though the docs example is slightly more than the minimum.

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 two-parameter informational tool with no output schema and no annotations, the description explains what is measured and what happens when the bar closes. It is complete enough to call correctly, though it could spell out the result shape more explicitly.

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 coverage is 100%, and the schema documents both `signal` and `now` in detail, so the description does not need to restate them. It adds no parameter-level syntax beyond that 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 states a specific resource—time remaining in a signal's bar—and enumerates the reported quantities (session minutes, wall-clock minutes, sessions left, fraction left). It is clearly distinguishable from signals_in_force or find_signals, though it does not name those siblings explicitly.

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?

It offers no explicit when-to-use or when-not guidance relative to siblings. The closest is "The tool reports time; it does not grade it," which sets a boundary but stops short of routing the agent to alternatives.

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