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

With no annotations supplied, the description carries the full burden and does substantially more than most: it states the tool takes no arguments, discloses that sibling tools reject out-of-coverage inputs, explains alias resolution ('bitcoin' or 'xbt' becomes a symbol), and flags cost ('One call costs one answer'). It does not describe response size, ordering, or whether results are cached, which for a coverage-dump tool would be useful.

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?

It is front-loaded with the payoff (what coverage you get) before the call-order rule and the sibling redirect, and there is no filler. Some phrasing is ornate rather than plain ('the first moment held and how far each scale reaches', 'one call costs one answer'), which costs a little immediate clarity on a first read.

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 annotations and no output schema, the description must explain what comes back, and it does so by enumerating the content categories and the alias-to-symbol mapping. What is missing is the shape of the response (flat list vs. sections) and its likely size, which matters for an unfiltered coverage dump.

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 tool has zero parameters, so there is no parameter meaning to add; the description correctly confirms 'Takes no arguments,' which matches the empty schema. Baseline of 4 applies for a 0-param tool with no semantic gap.

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 (list) and enumerates the exact resource contents: assets with names/aliases, data sources, earliest moment and scale reach, the scales themselves, and the condition phrasings query_history accepts. It is also explicitly distinguished from list_topics, so an agent can route between the two without opening a schema.

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 gives an explicit call-order instruction ('Call this before guessing a symbol, a scale, a date range or a phrasing') and the consequence of skipping it ('the other tools refuse what falls outside it'). It also names the alternative for a different need: 'For the kinds of recurring event the data is indexed by, use list_topics instead.'

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