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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds useful return context (expiry dates, days to expiry, strike counts) and the data source, but says nothing about completeness (all expirations? weeklies/monthlies?), ordering, or data freshness.

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?

The definition is a single front-loaded sentence with no filler. It is efficient, though the passive 'listed' phrasing is slightly awkward and it leaves out a natural chaining hint that would earn the fifth point.

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 must carry some return-value burden, and it does name the key fields. However, for a discovery tool feeding get_option_chain, it omits how to use the results and whether expirations are exhaustive, which leaves a meaningful gap.

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?

There is a single required symbol parameter with 100% schema description coverage, so the schema already explains it fully. The description does not add any format, normalization, or symbol-resolution details beyond the schema, making the baseline 3 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?

The description states a specific verb and resource: listing option expiry dates for a given symbol, and names the payload fields (days to expiry, number of strikes). It does not explicitly distinguish itself from siblings like get_option_chain or find_options, which likely also touch expirations, so it stops short of a 5.

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?

Usage is implied rather than stated: an agent can infer this is the discovery step before get_option_chain, but the description never says when to use this versus the chain or find_options. No exclusions, prerequisites, or alternatives are named.

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