List past runs

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

Annotations already cover the safety profile (readOnlyHint, openWorldHint=false), and the description's 'Read-only' only echoes them. It does add genuinely new behavior: results are sorted newest first, capped at 50 entries plus a total, and are discovered by scanning for run.json beneath the given directory.

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 action and ordering, then the return contents, then routing to the sibling tool. Dense but nearly every clause earns its place; only the trailing 'Read-only.' is redundant with the annotation.

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 two-parameter read tool with an output schema, the description covers the essentials: discovery scope, sort order, result cap, filterable field, and the alternative tool for full detail. No ambiguity that would cause a mis-invocation.

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 coverage is 100%, so the baseline is 3, but the description adds meaning: 'below runs_dir' implies a recursive scan for run.json files (the schema only says 'directory to search'), and `instrument` is framed as a comparison filter rather than a generic field.

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?

Specific verb and resource ('List past runs under a directory'), plus scope details (newest first, summary of each) that tell an agent exactly what comes back. It names a sibling (read_run_report) so the agent can distinguish it from the related report tool without opening either 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?

Clear context for use: scan a runs directory, optionally filter with `instrument` to compare runs on one market, and switch to `read_run_report` when a single run must be read in full. It names the alternative and the condition that selects it, though it gives no explicit when-not/negative cases.

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