history_coverage

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description's job is to add operational detail, and it does: it explains that coverage comes from yearly .hcc files, that an open year file is read with a single request bounded to that year, and that verify=true triggers one bounded UTC request for daily bars and ticks. It stops short of stating cost or latency implications of that verify request.

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 sentence one, but the remainder is dense and jargon-heavy, with terms like 'm1.time_from', '.hcc files', and 'one request bounded to that year' introduced without explanation. Nothing is gratuitous, yet the fragments read as notes rather than as guidance an agent can act on.

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 only two parameters, no output schema, and read-only annotations, this is close to complete for the tool's complexity. The main gap is that m1.time_from is cited as a return field without explaining the overall response shape (bar years, tick months, other fields), which matters precisely because no output schema exists.

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 0%, so the description must carry the parameter burden. It explains verify's behavior reasonably well ('one bounded UTC request ... for daily bars and for ticks') but says nothing about symbol beyond it being the target, and the schema's default of true for verify is not reconciled with the description's conditional phrasing.

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 states a specific verb and resource: reporting stored bar and tick depth for one symbol, with the scope-limiting clause 'without downloading a gap.' That distinguishes it in spirit from probe_history/extend_history, but those siblings are never named, so the differentiation is only implicit.

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?

The description conveys when-not behavior ('This call does not request an earlier year') and the effect of the verify flag, which implies usage conditions. However, it never names probe_history or extend_history as the tools to reach for when a gap actually needs filling, leaving the routing decision to inference.

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