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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), but the description adds substantial extra context: results reflect a completed session rather than live prices, outputs must preserve status/sample sizes/dates/warnings, and excess ranges are historical point returns against a date-matched baseline, not forecasts. These are meaningful behavioral disclosures beyond the structured fields.

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 "One call:" opener front-loads the summary and parameter semantics follow immediately, which is good structure. The remaining caveat block is dense and slightly repetitive, but each sentence (not real-time, don't treat vendor classification as sector, ranges are not forecasts) carries real interpretive value.

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?

An output schema exists, so return values need not be described, and the description instead spends its budget on interpretation caveats and preservation instructions, which is the right allocation. It is nearly complete; only the absence of explicit sibling routing keeps it from a 5.

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 carries the full burden and does it: symbol is defined as a stock ticker, date as an optional YYYY-MM-DD value, and the default behavior (omit date to get the latest built session) is spelled out. Both parameters are unambiguous as a result.

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 opens with an enumerated list of what comes back (completed-session state, tape, historical analogs, outcome ranges, transition memory) rather than a crisp verb+resource statement of purpose. An agent can infer this returns historical session context for a ticker, but the sentence mixes purpose with return contents and does not differentiate itself from the research-oriented siblings (daily_note, read_research, search_research).

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?

"Omit date for the latest built session, not real-time prices" and "No prior search needed" give concrete when-to-use guidance, and the caveats about vendor classification and excess ranges set boundaries on how to interpret results. It does not, however, explicitly contrast itself with the sibling research tools, so it stops short of full routing guidance.

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