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

Annotations already cover read-only/idempotent safety, but the description adds genuinely new operational context: required API key with two accepted header forms, and that calls count against a daily limit. It does not describe error behavior for non-weekday dates or missing editions.

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?

Dense but well front-loaded: resource, format, and edition semantics come first, with auth and rate-limit detail trailing. Every sentence carries load, though the auth sentence is packed enough to slow scanning slightly.

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 is responsible for framing the return, which it does implicitly ('a brief'). Combined with auth, rate limits, date-format constraints, and edition defaults, an agent has enough to invoke it correctly; only failure modes are unaddressed.

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 only 67%, and the description compensates: it adds the 'U.S. weekdays' constraint on date and explains the default behavior when edition is omitted, neither of which is in the schema. The 'format' parameter is left to its enum/default in the schema, which is acceptable.

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 ('A past MacroTape brief by date') with the date format and scope (U.S. weekdays) front-loaded. An agent can distinguish this from get_latest_brief purely from the 'past ... by date' framing.

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?

Gives clear selection logic for the edition parameter (omit -> newest edition that day) and a discovery path ('List available dates with the open /api/index.json'). It stops short of explicitly naming get_latest_brief as the alternative for current briefs, leaving that routing to inference.

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