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

Annotations already cover readOnly/idempotent safety. The description adds real behavioral value beyond them: the truncation policy for anonymous and free-tier callers, the no-alteration/no-interpolation guarantee, and the freshness/truncated/available_points metadata. It stops short of stating rate limits or auth requirements explicitly.

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?

Front-loads the purpose and return shape, then example, then constraints. It is information-dense but the long inline return-field enumeration and the meta-justification about not changing figures are slightly verbose; still, every clause carries usable signal.

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?

Covers purpose, scope, return field names, valid enum values, example call, and access-tier truncation behavior. With no output schema, the inline field list is appropriate; the only gap is explicit routing to sibling tools for current readings.

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%, so baseline is 3, but the description adds meaning: it enumerates the valid signal_type values and gives a concrete example call with days=30, plus explains the returned string('date, signal_strength 0-100, direction'). This enriches the semantics of both parameters.

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 ('Dated strength history for one CoinBucha signal'), specifies a single signal scope, and notes ordering ('newest first'). An agent can distinguish it from sibling scan_signals or the per-signal getters that return current readings.

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?

Clear context (history for one named signal) and it indirectly signals the alternative scanning/current tools by its naming, but it never explicitly names a sibling or states when-not to use this tool (e.g., versus scan_signals for current readings). Strong context without explicit routing.

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