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

Annotations already declare read-only, idempotent, and non-destructive, but the description adds substantial behavioral detail: timeline capping at 200 events, span capping at 2,000, truncation flags, terminal event always present, span ordering rules, outcome semantics including the unfinished case, and the untrusted_fields security warning. This goes well beyond what annotations convey.

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?

Long but densely informative with no filler; every sentence adds distinct value, from auth requirements to truncation behavior to output wrapping. Key details are front-loaded: purpose first, then usage context, then edge-case semantics.

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 complex read tool with no output schema, the description covers all the nuances an agent needs: event ordering, verdict semantics, truncation caps, outcome values, span shape, GenAI block conditionality, and result wrapping. Together with the annotations, this is fully actionable.

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%, so the schema already documents both id and rid fully. The description mentions id + rid as the pairing needed to target a run, but does not add meaningful parameter-specific semantics beyond what the schema already provides. Baseline 3 is appropriate.

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 clear, specific purpose: get ONE run's full timeline, not a summary. It enumerates exactly what is included (events, assertions, terminal output, CI metadata, OTLP spans) and distinguishes itself from get_run_history and list_open_incidents, which provide more limited views.

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?

Explicitly says when to use it: after get_run_history or list_open_incidents has identified a specific run and you need the detailed blow-by-blow rather than the summary row. It also names the relevant alternative tools, making the selection decision clear. The read-scope requirement further frames appropriate usage.

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