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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description adds genuinely useful context by enumerating the analytical outputs (open_location, open_type classification set, tails, scenario_framing, invalidation level), which the agent could not infer from schema or annotations. It does not mention cost/reproducibility of supplying candles, which the schema already states.

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-loaded with the purpose, then usage triggers, then a compact semicolon-delimited return inventory. The return list is dense but every field named is meaningful and there is no filler prose.

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, the description carries the burden of explaining return values and does so thoroughly (open classification, key levels, tails, scenario framing, invalidation). For a read-only analytical workflow with full schema coverage, the definition supplies everything an agent needs to call and interpret it.

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% and all seven parameters are documented in the schema (venue enum, timeframe enum, value_area_rule range, candles reproducibility note). The description adds almost no parameter-level meaning beyond that; baseline 3 is appropriate when the schema does the heavy lifting.

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: 'Market Profile open analysis: where and how price opened vs the prior session value area.' The example queries ('how did BTC open today?') make the analysis target unambiguous. It does not, however, explicitly distinguish itself from adjacent siblings like workflow.run_session_structure, so a 4 rather than a 5.

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 quoted user questions ('how did BTC open today?', 'what does the open imply for the session?') give concrete triggers for selecting this tool. There is no statement of when NOT to use it or which sibling to prefer for related session-structure questions, so it stops short of a 5.

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