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

Annotations already cover readOnly/idempotent/non-destructive/openWorld=false. The description adds genuinely new operational context: retention is limited to 48 hours, unknown instruments return UNKNOWN_INSTRUMENT, and the accepted instrument categories. It omits return format and pagination, but those are covered by the output schema.

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 core behavior, then differentiation, then error handling and constraints. Every sentence carries information, though the closing compliance line ('Information only — never investment advice') is boilerplate that lengthens the block 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?

Covers what the tool returns, the 48-hour retention bound, the untracked-instrument failure path with a recovery tool, and the accepted instrument vocabulary. With an output schema present, return-value detail is rightly delegated, so nothing an agent needs is missing.

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 goes further by enumerating concrete valid inputs ('Reliance', 'HDFCBANK', 'crude oil', 'gold', 'Nifty', 'rupee', 'repo rate') that clarify ambiguous categories like commodity vs index. It does not address hours/limit/cursor, which the schema handles.

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+resource ('News stories linked to one instrument') plus ordering ('newest first') and scope ('for one country'). It also explicitly distinguishes itself from search_stories: word-matching vs instrument-linked. An agent can pick it without opening the 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?

Names the alternative (search_stories) and the exact condition that separates them ('matches words' vs 'linked to that instrument'), and routes to list_instruments when the instrument is untracked. It also states the UNKNOWN_INSTRUMENT failure mode, so the agent knows what happens before it calls.

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