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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, but the description goes further: stateless edge call, 32 KB payload cap, 60 RPM rate limit, '?demo=true' or L402 payment (15 sats), and HTTP 400 on invalid input. These operational constraints are exactly the kind of context annotations cannot express.

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?

Two sentences, with purpose front-loaded and the sibling reroute placed before the operational parenthetical. The constraints sentence is dense and run-on (size, rate limit, auth, error code all crammed into one clause), which slightly hurts scannability, but no sentence is 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?

An output schema exists so return values need not be described, annotations cover the safety profile, and the description supplies the non-obvious operational envelope (size, rate, payment, error). An agent has everything needed to call this correctly and to know when to route elsewhere.

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% and each parameter is documented in-schema, so the baseline is 3. The description adds only the default value for 'timeline_resolution' and the name of the required input; it says nothing about 'ascending_order' behavior or the practical difference between the three resolution modes.

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and resource ('Synthesizes chronological milestone timelines') plus the input sources (search results, news archives, historical documents). It also names the sibling it is not (analyze_news_recency), so an agent can distinguish the two without opening schemas.

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 concrete usage cases (reconstructing historical events, company histories, regulatory progression) and an explicit exclusion with the alternative for the 24-hour breaking-news case. Nothing about tool selection is left to inference.

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