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

The readOnlyHint annotation already covers safety. The description adds useful behavioral context: results are ordered newest first, each row contains specific fields, and created_by_key_name is null for browser-launched runs. It does not disclose pagination or result limits.

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 description is front-loaded with the primary behavior and efficiently lists return fields. The trailing sentence 'Returns runs.' is redundant with the opening verb and slightly weakens conciseness.

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 read-only list tool with one optional parameter and no output schema, the description adequately explains scope, ordering, and returned fields. Missing pagination/limit details and sibling-tool routing keep it from being fully complete.

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% and the schema already documents quote_id, so baseline is 3. The description adds meaning by clarifying the default scope when quote_id is omitted ('every run of this key's owner') and the filtered scope when it is given ('one quote's runs').

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 names a specific verb and resource ('List runs') and states the scope: all runs for the key's owner, or one quote's runs when quote_id is given. It does not explicitly differentiate from siblings like mcg_get_run, but the list-vs-get distinction is clear from the tool name and description.

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?

It clearly describes the two modes: default all runs of the owner, or filtered to one quote's runs when quote_id is provided. There is no explicit guidance on when to choose this over alternatives, but the usage context is unambiguous.

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