get_observable

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

Annotations already cover the read-only, idempotent, non-destructive profile, so the description earns credit for something annotations cannot express: the explicit warning that returned text fields are third-party CTI content and must be treated as untrusted data rather than instructions. That is real, actionable behavioral guidance.

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?

Two sentences, front-loaded with the payload contents and closed with the safety caveat. Nothing redundant, nothing padded.

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 and full param coverage, the definition is nearly complete for a simple two-parameter read. Minor residual gaps: no guidance on not-found behavior and no disambiguation from lookup_observable among five siblings.

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%, with the id format (UUID or STIX 'ipv4-addr--<uuid>') and the 20-item 'newest first' relation cap already documented on the parameters. The description's 'optionally its relationships' merely restates the relations flag, adding no new semantics.

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?

A specific verb (fetch) plus resource (one observable) with an unusually precise inventory of what comes back: score, labels, markings, hashes, external references, linked indicators, containing reports. The one gap is that it never distinguishes itself from the sibling lookup_observable, which by name sounds like it does something very similar.

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 only implied by the required 'id' parameter — retrieve a single observable you already have an id for. There is no statement of when to prefer this over lookup_observable or get_indicator, and no exclusions for the search_* siblings.

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