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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely new behavior: it returns full markdown text of a section, and with no section argument it switches modes to return a table of contents with previews. It does not cover fuzzy-match failure or missing-section behavior.

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?

Three tight sentences: purpose, output/fallback behavior, then usage trigger — correctly front-loaded with no filler. The third sentence slightly reprises the opening verb phrase, which is the only minor redundancy.

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 an output schema present, return values needn't be detailed, and annotations carry the safety profile; the description still supplies the dual-mode behavior that is not visible in the schema. Minor gaps remain around invalid/ambiguous section names and how to discover valid section names, but nothing essential to calling it 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% and the schema already documents year defaults, ticker format, and that section is fuzzy matched and optional ("Omit to get TOC"). The description's section examples and omit-behavior duplicate what the schema states, adding little semantics beyond it, so the baseline 3 applies.

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 ("Read a specific section of an NZX company annual report") and clarifies the unit of retrieval (markdown text of one section), which separates it from report-listing siblings like get_annual_reports and from analysis siblings like get_annual_report_quality. It never names an alternative tool, so differentiation is implied by scope rather than stated.

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?

"Use when asked to read, quote, or summarise a specific part of an annual report" gives a clear positive trigger, and the fallback sentence tells the agent what happens when no section is given. There is no explicit when-not guidance or routing to a discovery tool for finding tickers/years, so it stops short of 5.

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