Gopher & Gemini MCP Server

Inspect Gemini trust store

gemini_trust_list

Read-only

List pinned Gemini server certificates to verify a host's trust-on-first-use fingerprint, check expiry, and diagnose certificate changes.

Instructions

List the Gemini server certificates this server has pinned.

Gemini has no certificate authorities. The first certificate seen for a host is pinned (trust on first use) and every later connection must present that same certificate, so this store is the only thing that authenticates a Gemini server. This tool reads it and never changes it.

This is the server half: the certificate a capsule presents to US. Our own identity -- the client certificate this server presents to a capsule -- is a separate store, read with gemini_client_cert_list and changed with gemini_client_cert_update. The two are unrelated, and nothing here is a private key of the user's.

Use it to explain a CERTIFICATE_CHANGED failure: it reports the fingerprint currently pinned, when it was first seen and when the certificate expires, which is what makes a routine reissue plausible or implausible. It is also the source of the fingerprint gemini_trust_update requires before it will drop a pin.

Returns: The pinned entries matching the request, each with its host, port, SHA-256 fingerprint, first/last seen timestamps and expiry.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`host`	No	Hostname to report on, e.g. geminiprotocol.net . Omit to list every pinned host -- which is in effect the list of capsules this user has visited, so name the host you are actually asking about unless the user wants the whole store.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Addedv0.10.2Sep 8, 2026

TDQS

A4.7/5.0

Behavior5/5

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

The description goes well beyond the readOnlyHint annotation by explaining the trust-on-first-use mechanism, clarifying that the tool never modifies the store, and reassuring that nothing here is a private key. It also discloses what data is returned, giving the agent a clear model of the operation's effect and output.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Although the description is multi-paragraph, every sentence provides necessary context: purpose, protocol background, relationship to other stores, use cases, and return values. The main action is front-loaded in the first sentence, and the structure flows logically from what to why to when to what-comes-back.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with one optional parameter, a read-only annotation, an output schema, and a well-defined niche among siblings, the description covers all needed context: the protocol's unique trust model, the distinction from client certificates, the operational use cases, and the exact return fields. Nothing an agent needs to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, and the single 'host' parameter is already richly documented with an example and guidance to omit it for the full store. The tool description adds only a passing reference to 'matching entries,' so the schema carries the semantic weight; the baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource: 'List the Gemini server certificates this server has pinned.' It clearly distinguishes this tool from siblings like gemini_client_cert_list and gemini_trust_update by explaining the server-half versus client-half split and the relationship to pin updates.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use the tool: to explain a CERTIFICATE_CHANGED failure and to obtain the fingerprint required by gemini_trust_update. It also tells the agent what this tool is not for by contrasting it with the client certificate store, leaving no ambiguity about selection among sibling tools.

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

Deploy Server