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

readOnlyHint=true already establishes the safe-read profile, so the bar is lower; the description adds real value by naming the return fields and explaining the contact_id format (MD5 of lowercased email, or the id from list_contacts). It stops short of covering error behavior for a missing contact.

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, return shape, then ID derivation and endpoint. Front-loaded with zero filler and no 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 no output schema, the description usefully enumerates the return fields and explains the ID format, making the tool callable without guessing. It lacks only failure-mode context (e.g., behavior when the contact does not exist).

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 both parameters are already documented; the description's contact_id explanation largely restates the schema's own wording. Per the baseline rule, a 3 is appropriate when the schema does the heavy lifting.

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 ('Get a single contact in a list') and enumerates the returned fields, so the agent knows exactly what this retrieves. It does not explicitly distinguish itself from the sibling list_contacts beyond the singular/plural implication, which keeps it from 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 by 'single contact' versus the sibling emailoctopus_list_contacts, but the description never states when to choose one over the other or any exclusion. The mention of list_contacts is about deriving contact_id, not about tool selection.

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