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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, yet the description still adds substantial context: nothing is persisted, gold calculators fetch live prices and report a price date, prices-unavailable yields an error rather than a guess, and invalid inputs fail with a message naming the field. It also flags that results are indicative and not a fatwa or medical advice, which the agent needs to relay.

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 core action and return format are front-loaded in the first sentence, and the subsequent sentences each carry distinct information (persistence, live-price behavior, validation errors, disclaimers). It is slightly long but no sentence is redundant.

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 no output schema and a nested free-form inputs object, the description does a good job explaining what comes back (JSON matching the website's numbers) and how failures surface. The one remaining gap is that the per-calculator input names live entirely in list_calculators output rather than here, though the description points there 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 description coverage is 100%, so id and inputs are already documented including the YYYY-MM-DD and EGP-per-gram conventions. The description only reinforces that id comes from list_calculators and that failures name the offending field, adding little beyond the schema; the baseline of 3 applies.

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 first sentence gives a specific verb and resource ("Runs one calculator from list_calculators and returns its result as JSON") and ties the tool to the discovery sibling list_calculators. It does not, however, distinguish itself from the sibling tool named calculate, which an agent would reasonably see as overlapping.

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?

Usage is implied through the prerequisite that the id must come from list_calculators, which gives the agent a workflow. There is no explicit when-to-use or when-not-to-use guidance, and nothing explains how this differs from the calculate sibling, so the agent must infer the choice.

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