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

readOnlyHint=true already tells the agent this is a safe read; openWorldHint covers the external scope. The description adds default behavior and a hard cap of 20 periods, which is genuine operational context, but says nothing about auth needs, rate limits, or what 'normalized' transforms. Credits a bit above the annotation floor, consistent with a 3.

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 sentences, zero waste: purpose and input forms first, defaults/cap second, alternative routing last. Everything is front-loaded and earns its place.

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 no explanation, parameter coverage is full, and annotations carry the safety profile. The definition is nearly complete; only minor gaps like error/edge behavior or the meaning of 'normalized' keep it from a 5.

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 every parameter (cik, ticker, statement, period, limit) is already documented including defaults and the max. The description only restates those defaults, adding no syntax or format meaning beyond the schema. 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 (Fetch), resource (normalized SEC financial statements), and scope (one company by cik or ticker). It also names the sibling (sec_frames) it is not, so an agent can separate it from other SEC/finance tools without opening a 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?

Explicitly routes the agent to sec_frames for the contrasting use case (comparing one XBRL concept across companies), which is precisely the condition that selects the alternative. The single-alternative routing matches the calibration's top-scoring pattern.

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