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

Annotations already declare readOnly/openWorld/idempotent behavior, so the bar is lower. The description adds valuable behavioral context beyond annotations: it reveals that rejected backtests are retrievable and that out-of-namespace run_ids return 'not found' rather than an error. No contradiction with annotations.

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?

Three concise sentences with the core purpose front-loaded, followed by the namespace caveat and parameter guidance. Every sentence adds useful information with no redundancy or filler.

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?

For a simple single-parameter retrieval tool with an output schema present, the description covers everything an agent needs: how to identify the run, where the handle comes from, and the namespace visibility behavior. No critical gaps.

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 for the single parameter. It compensates well by explaining the format (`twmd_bt_…` handle) and provenance (returned by run_backtest), adding meaning far beyond the bare schema property.

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 ('Retrieve'), resource ('previous backtest'), and key ('run_id'), and clarifies it returns the full record including rejection reasons. This clearly distinguishes it from siblings like run_backtest, replay_backtest, and list_backtests.

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?

Provides clear context for when to use the tool—retrieving a prior backtest by run_id—and adds an important namespace exclusion (others' run_ids are simply not found). It does not explicitly name alternative tools, but the usage context is strong and unambiguous.

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