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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds value beyond them by disclosing the return format (JSON, deliberately not CSV, and why) and by surfacing the isPartialPeriod response field that governs interpretation of weekly/monthly results. It does not mention rate limits or auth, keeping it short of a 5.

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 resource and its contents, then the two disambiguating facts (partial-period semantics, JSON-not-CSV). Slightly redundant: the partial-period rule is repeated almost verbatim in the period parameter description, costing a little density but not clarity.

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 carries the return-value burden and does so: it names the response shape (a bundle of small lists), the format (JSON), and the key interpretive field (isPartialPeriod). Combined with full schema coverage and annotations, an agent has everything needed to call and interpret this correctly.

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 date, limit, and period semantics, including the mid-period behavior for weekly/monthly. The description restates the period/partial-period interaction rather than adding syntax, bounds, or format details the schema lacks; 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 specific verb ('Get') and resource ('market summary') and enumerates exactly what the bundle contains: top gainers/losers, volume/turnover/crossings, ASI and S&P SL20 performance, and sector performance. This clearly separates it from siblings like get_index_data (single index) and screen_stocks (filtering), so an agent can route 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 clear context for the tricky case — a weekly/monthly summary requested mid-period covers the in-progress period, not the prior complete one — which is exactly the ambiguity an agent would otherwise guess wrong on. It stops short of naming alternatives (e.g. when to prefer get_index_data or screen_stocks instead), so it is clear context without explicit exclusions.

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